<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:eb1a0ae9-c5b4-4aa5-9a7a-e68fa4284625,g:6817a022-14b1-4e96-9e47-08a8b3008d3a-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.tradeweb.com/role/Cover" xlink:type="simple" xlink:href="tw-20240630.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_9d079e0e-d302-4c0d-acd2-9890185a25f8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntitiesTable_9d079e0e-d302-4c0d-acd2-9890185a25f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8c5f8f8b-a70d-4b48-a740-9991a63b99fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_9d079e0e-d302-4c0d-acd2-9890185a25f8" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8c5f8f8b-a70d-4b48-a740-9991a63b99fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8c5f8f8b-a70d-4b48-a740-9991a63b99fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8c5f8f8b-a70d-4b48-a740-9991a63b99fd" xlink:to="loc_us-gaap_ClassOfStockDomain_8c5f8f8b-a70d-4b48-a740-9991a63b99fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8c5f8f8b-a70d-4b48-a740-9991a63b99fd" xlink:to="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_9fbff8eb-1af3-4e41-bd32-46b9d853e510" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:to="loc_us-gaap_CommonClassAMember_9fbff8eb-1af3-4e41-bd32-46b9d853e510" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_02fa293b-61fe-49be-93de-4bdf28f5fa97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:to="loc_us-gaap_CommonClassBMember_02fa293b-61fe-49be-93de-4bdf28f5fa97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_6897ab5c-d14d-4018-ae9b-462833a70dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:to="loc_us-gaap_CommonClassCMember_6897ab5c-d14d-4018-ae9b-462833a70dfc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_4816e3fe-2aa0-4b4c-9cb8-2201c6596af6" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_70cdb746-2175-4369-99a1-d1d74977aa36" xlink:to="loc_tw_CommonClassDMember_4816e3fe-2aa0-4b4c-9cb8-2201c6596af6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_93a29c0f-2a5a-4f0f-a567-362a9896cbea" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentType_93a29c0f-2a5a-4f0f-a567-362a9896cbea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_4a868b37-68df-4248-aaed-cb246aff071f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentQuarterlyReport_4a868b37-68df-4248-aaed-cb246aff071f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_a2293ae5-12dd-4801-9ffe-a4dad5fe4c55" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentPeriodEndDate_a2293ae5-12dd-4801-9ffe-a4dad5fe4c55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_1ebe63af-7a72-415e-b9e2-e2408941fc08" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentTransitionReport_1ebe63af-7a72-415e-b9e2-e2408941fc08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_a70d8ee0-d4f8-4a0d-a161-1c4b88830eee" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityFileNumber_a70d8ee0-d4f8-4a0d-a161-1c4b88830eee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_49a108aa-e849-41be-839e-6e019edfa8cc" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityRegistrantName_49a108aa-e849-41be-839e-6e019edfa8cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_58af8a0e-05a8-43f6-9dc6-51eb4da63b86" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityIncorporationStateCountryCode_58af8a0e-05a8-43f6-9dc6-51eb4da63b86" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_65863f3d-de51-4f68-ad8d-ee1f5b8af0d7" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityTaxIdentificationNumber_65863f3d-de51-4f68-ad8d-ee1f5b8af0d7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_e570ec4b-b314-4e62-b246-b9a6bc3da774" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityAddressAddressLine1_e570ec4b-b314-4e62-b246-b9a6bc3da774" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_736c6c6a-0122-4f60-b5a2-892c486e77ce" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityAddressCityOrTown_736c6c6a-0122-4f60-b5a2-892c486e77ce" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_f94dca16-832b-4ca5-bdc3-6b64faee1b64" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityAddressStateOrProvince_f94dca16-832b-4ca5-bdc3-6b64faee1b64" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_98184c83-ee13-425d-b999-6a17144308a6" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityAddressPostalZipCode_98184c83-ee13-425d-b999-6a17144308a6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_34ce8b16-6343-4cf8-af0b-c1748f4fe68a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_CityAreaCode_34ce8b16-6343-4cf8-af0b-c1748f4fe68a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_cb9f7786-e832-47fb-aa41-4e9458418949" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_LocalPhoneNumber_cb9f7786-e832-47fb-aa41-4e9458418949" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_1530ed7f-c14f-429a-b538-4ed99b32d182" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_Security12bTitle_1530ed7f-c14f-429a-b538-4ed99b32d182" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_2c6b9157-e67b-4619-b613-a7f2bebf3c4b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_TradingSymbol_2c6b9157-e67b-4619-b613-a7f2bebf3c4b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_bfb06982-17df-412a-ac1b-b43955ba23f2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_SecurityExchangeName_bfb06982-17df-412a-ac1b-b43955ba23f2" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_3286c985-5d89-4473-8592-cf88c51be6b3" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityCurrentReportingStatus_3286c985-5d89-4473-8592-cf88c51be6b3" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_ed772636-8315-40b5-8698-b4d3d9f7a118" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityInteractiveDataCurrent_ed772636-8315-40b5-8698-b4d3d9f7a118" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_080f895c-4a70-414b-88f3-8eebd228117b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityFilerCategory_080f895c-4a70-414b-88f3-8eebd228117b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_9f5fd09c-8c5f-419c-9ffa-dfadd2c39e53" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntitySmallBusiness_9f5fd09c-8c5f-419c-9ffa-dfadd2c39e53" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_604c3c38-72df-48f2-99e9-9133ecf768f0" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityEmergingGrowthCompany_604c3c38-72df-48f2-99e9-9133ecf768f0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_47503c90-a7f2-4350-a2a3-5804426a180f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityShellCompany_47503c90-a7f2-4350-a2a3-5804426a180f" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_9e47fd64-5208-4ed5-8032-f29e3db4406c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_9e47fd64-5208-4ed5-8032-f29e3db4406c" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_657da563-b02a-4ac7-86be-d8b94f2da10a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_EntityCentralIndexKey_657da563-b02a-4ac7-86be-d8b94f2da10a" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_50a6fb89-5448-4550-9d8d-1f120658ca23" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_CurrentFiscalYearEndDate_50a6fb89-5448-4550-9d8d-1f120658ca23" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_2c3f5535-5960-4bf1-aa57-8bf9a66038ce" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentFiscalYearFocus_2c3f5535-5960-4bf1-aa57-8bf9a66038ce" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_291befc8-a1f7-4749-92f5-b8f556e01ffc" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_DocumentFiscalPeriodFocus_291befc8-a1f7-4749-92f5-b8f556e01ffc" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_e3627894-f5f2-4493-9b05-f457220c4197" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_297dc758-b1ad-4929-91a5-c38bc697a35f" xlink:to="loc_dei_AmendmentFlag_e3627894-f5f2-4493-9b05-f457220c4197" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofFinancialCondition" xlink:type="simple" xlink:href="tw-20240630.xsd#CondensedConsolidatedStatementsofFinancialCondition"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofFinancialCondition" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_3325cee8-3371-4c33-9b29-1e04c4d560a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_9f416309-30d6-4721-b9aa-3d024b103b5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_3325cee8-3371-4c33-9b29-1e04c4d560a5" xlink:to="loc_us-gaap_StatementTable_9f416309-30d6-4721-b9aa-3d024b103b5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_e896694e-1815-4a89-a161-26d5d6f37cd9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_9f416309-30d6-4721-b9aa-3d024b103b5d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_e896694e-1815-4a89-a161-26d5d6f37cd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e896694e-1815-4a89-a161-26d5d6f37cd9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e896694e-1815-4a89-a161-26d5d6f37cd9" xlink:to="loc_us-gaap_ClassOfStockDomain_e896694e-1815-4a89-a161-26d5d6f37cd9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e896694e-1815-4a89-a161-26d5d6f37cd9" xlink:to="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_18a92843-c816-447d-8f49-ac8ec29c6435" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:to="loc_us-gaap_CommonClassAMember_18a92843-c816-447d-8f49-ac8ec29c6435" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_281737a0-0572-45c6-880a-805a8f16a46a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:to="loc_us-gaap_CommonClassBMember_281737a0-0572-45c6-880a-805a8f16a46a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_da15e3ad-5792-494b-bfb2-29112f8b69b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:to="loc_us-gaap_CommonClassCMember_da15e3ad-5792-494b-bfb2-29112f8b69b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_8c15402a-09cc-46d4-b20a-20ca15cd4601" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_930cd420-630e-410f-b18f-202dcf008647" xlink:to="loc_tw_CommonClassDMember_8c15402a-09cc-46d4-b20a-20ca15cd4601" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3325cee8-3371-4c33-9b29-1e04c4d560a5" xlink:to="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_3cdd0e77-18a9-4b73-acb1-5f6ea65d7cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_3cdd0e77-18a9-4b73-acb1-5f6ea65d7cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_e9b5c852-e291-4740-8a9b-473c796d3304" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_RestrictedCash_e9b5c852-e291-4740-8a9b-473c796d3304" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_dc125ab6-a28e-4014-9d88-87a7aa1f4dc8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_dc125ab6-a28e-4014-9d88-87a7aa1f4dc8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities_2b31e4ac-7804-4871-a76d-24b865c89178" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities_2b31e4ac-7804-4871-a76d-24b865c89178" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_68b53f01-ef80-4337-a369-43a5a74a7839" xlink:href="tw-20240630.xsd#tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_68b53f01-ef80-4337-a369-43a5a74a7839" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_c092734a-e79b-4716-9b1a-dcdc37d0c23b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_c092734a-e79b-4716-9b1a-dcdc37d0c23b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_d8bac872-64a2-44fe-a3e6-b3a0ea0944fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_d8bac872-64a2-44fe-a3e6-b3a0ea0944fc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareNet_bb640d31-56b4-43b7-90d9-7103907e55f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CapitalizedComputerSoftwareNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_CapitalizedComputerSoftwareNet_bb640d31-56b4-43b7-90d9-7103907e55f8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_9d249769-0eba-401b-80d4-5cf5acb4c42e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_Goodwill_9d249769-0eba-401b-80d4-5cf5acb4c42e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_e1d9f573-a86b-422b-953b-4054d7f94a7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_e1d9f573-a86b-422b-953b-4054d7f94a7f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivables_b143b806-d666-48c2-b12b-6ae820e37a33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_OtherReceivables_b143b806-d666-48c2-b12b-6ae820e37a33" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_15856520-6742-4d6a-9f42-5744100ed44f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_15856520-6742-4d6a-9f42-5744100ed44f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_7cdcc5c3-2c10-49ca-88fb-ee250cd2e363" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_OtherAssets_7cdcc5c3-2c10-49ca-88fb-ee250cd2e363" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_55183477-ff68-4f06-ba1f-4bbed5b6f316" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_bc1be93e-7dd4-4aea-a1b0-43d5f34604ce" xlink:to="loc_us-gaap_Assets_55183477-ff68-4f06-ba1f-4bbed5b6f316" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3325cee8-3371-4c33-9b29-1e04c4d560a5" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:to="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_fdb2e542-db62-41ab-ba93-77a609dd1db4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_fdb2e542-db62-41ab-ba93-77a609dd1db4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_b936bb98-f636-4a42-b9cf-1170c3ddeb6c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_b936bb98-f636-4a42-b9cf-1170c3ddeb6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_b61d1c4f-669c-4788-921a-b56bfc9f936b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_b61d1c4f-669c-4788-921a-b56bfc9f936b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_37926d93-f7d9-448b-9917-5eda914a4068" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_ContractWithCustomerLiability_37926d93-f7d9-448b-9917-5eda914a4068" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_2a6bc9a7-7d2b-4ea8-bcd9-194a74d8a2cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_2a6bc9a7-7d2b-4ea8-bcd9-194a74d8a2cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_6093ba98-a01a-4cc9-96d5-733801384ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_OperatingLeaseLiability_6093ba98-a01a-4cc9-96d5-733801384ce4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_07925c40-baf5-4d61-9626-29059d710178" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_OtherLiabilities_07925c40-baf5-4d61-9626-29059d710178" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_e2135dd5-120a-4483-b2c3-2db59e4dc332" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_e2135dd5-120a-4483-b2c3-2db59e4dc332" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TaxReceivableAgreementLiability_98b9f26a-f83c-4106-8c70-5c61c60a6e94" xlink:href="tw-20240630.xsd#tw_TaxReceivableAgreementLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_tw_TaxReceivableAgreementLiability_98b9f26a-f83c-4106-8c70-5c61c60a6e94" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_91727724-eafc-4df4-a109-bbee3a22740b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_98ce5261-c3a0-41d6-95c1-982bc6ebbcde" xlink:to="loc_us-gaap_Liabilities_91727724-eafc-4df4-a109-bbee3a22740b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_ebeb1bf9-050d-4208-92e9-c72e7c57a3f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:to="loc_us-gaap_CommitmentsAndContingencies_ebeb1bf9-050d-4208-92e9-c72e7c57a3f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MembersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:to="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_48a85794-7567-4e04-a5ab-16bc1c43dc77" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_PreferredStockValue_48a85794-7567-4e04-a5ab-16bc1c43dc77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_a2ca25b1-f29b-4298-9eb2-e11c9d10d4ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_CommonStockValue_a2ca25b1-f29b-4298-9eb2-e11c9d10d4ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_4f7a57a8-c9e5-435c-ba69-3019093cb135" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_AdditionalPaidInCapital_4f7a57a8-c9e5-435c-ba69-3019093cb135" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_79b2818b-fbdd-4637-b4db-31ee84c98c7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_79b2818b-fbdd-4637-b4db-31ee84c98c7f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_55e41fbb-52c7-4f84-8947-4403af759b3c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_55e41fbb-52c7-4f84-8947-4403af759b3c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_54948e30-16ac-4c02-a305-235525277385" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_StockholdersEquity_54948e30-16ac-4c02-a305-235525277385" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_d544066e-8474-4585-8ad2-dadb5fd3b87e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_MinorityInterest_d544066e-8474-4585-8ad2-dadb5fd3b87e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9485270a-6f5a-4eaa-b3ef-e68682b41ed9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_6ef103b4-21b5-4b29-b619-05d628ae256f" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9485270a-6f5a-4eaa-b3ef-e68682b41ed9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_d5d7b90c-63c6-4c4e-90ed-f830b97b2f22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_86fc1539-1de0-4984-91bc-c2422215e196" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_d5d7b90c-63c6-4c4e-90ed-f830b97b2f22" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofFinancialConditionParenthetical" xlink:type="simple" xlink:href="tw-20240630.xsd#CondensedConsolidatedStatementsofFinancialConditionParenthetical"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofFinancialConditionParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_dfd36510-dd1c-4acf-ab0e-078d239eabc2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_StatementTable_dfd36510-dd1c-4acf-ab0e-078d239eabc2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_dfd36510-dd1c-4acf-ab0e-078d239eabc2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c" xlink:to="loc_us-gaap_ClassOfStockDomain_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9a2bb3fb-6c9a-4a97-ba96-623faf5abe6c" xlink:to="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_cc40f3e7-0a45-4922-8199-4b47eecb82bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:to="loc_us-gaap_CommonClassAMember_cc40f3e7-0a45-4922-8199-4b47eecb82bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_e5d0058c-930c-4ff4-8e3f-1ecb68cdbcf4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:to="loc_us-gaap_CommonClassBMember_e5d0058c-930c-4ff4-8e3f-1ecb68cdbcf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_d07ba0b0-6dfa-47ba-bb5c-a94ce3f8da24" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:to="loc_us-gaap_CommonClassCMember_d07ba0b0-6dfa-47ba-bb5c-a94ce3f8da24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_d99e75dd-8482-42ef-bec0-708aede8fd51" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_47db5a17-323a-4779-bf5a-8618a5960656" xlink:to="loc_tw_CommonClassDMember_d99e75dd-8482-42ef-bec0-708aede8fd51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_0ed294f7-1f6b-4623-b827-3940ba5bb4a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_0ed294f7-1f6b-4623-b827-3940ba5bb4a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_e5ad2f87-f5e5-4f5a-a104-35fce5d07c01" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_e5ad2f87-f5e5-4f5a-a104-35fce5d07c01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_db542911-ceb0-422c-b183-e91375591988" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_db542911-ceb0-422c-b183-e91375591988" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_697003f4-d60d-484d-85f9-5d17466eb082" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_PreferredStockSharesIssued_697003f4-d60d-484d-85f9-5d17466eb082" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_5ab59f11-5660-44d9-ac1a-1f0e0380640d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_5ab59f11-5660-44d9-ac1a-1f0e0380640d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_7a3341b3-fcff-45ac-a6bd-1f32be3f6bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_7a3341b3-fcff-45ac-a6bd-1f32be3f6bf8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_dc200e82-5b85-405c-846c-45482a8ea152" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_dc200e82-5b85-405c-846c-45482a8ea152" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_8e10b12d-da8a-4dbc-891c-dd8ff390268b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_CommonStockSharesIssued_8e10b12d-da8a-4dbc-891c-dd8ff390268b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_2290d739-b27c-4396-8572-31a39d3fa3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b9e8d926-4ec4-4840-8a2f-1545eab0a038" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_2290d739-b27c-4396-8572-31a39d3fa3b0" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofIncome" xlink:type="simple" xlink:href="tw-20240630.xsd#CondensedConsolidatedStatementsofIncome"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1d7bbc7f-9d81-4ef5-966e-fca15eb31c67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_StatementTable_1d7bbc7f-9d81-4ef5-966e-fca15eb31c67" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_2206d874-48d6-4b79-b43c-49a6a5b18806" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1d7bbc7f-9d81-4ef5-966e-fca15eb31c67" xlink:to="loc_srt_ProductOrServiceAxis_2206d874-48d6-4b79-b43c-49a6a5b18806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2206d874-48d6-4b79-b43c-49a6a5b18806_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_2206d874-48d6-4b79-b43c-49a6a5b18806" xlink:to="loc_srt_ProductsAndServicesDomain_2206d874-48d6-4b79-b43c-49a6a5b18806_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_2206d874-48d6-4b79-b43c-49a6a5b18806" xlink:to="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TransactionFeeRevenueMember_789959c6-4410-4c4a-8dbf-a02993d9d87f" xlink:href="tw-20240630.xsd#tw_TransactionFeeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:to="loc_tw_TransactionFeeRevenueMember_789959c6-4410-4c4a-8dbf-a02993d9d87f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_SubscriptionFeeRevenueMember_d2d1de61-34aa-4a43-a86e-4d325683926f" xlink:href="tw-20240630.xsd#tw_SubscriptionFeeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:to="loc_tw_SubscriptionFeeRevenueMember_d2d1de61-34aa-4a43-a86e-4d325683926f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MarketDataRevenueMember_40d5b9b0-04fd-4604-a6fe-e5a48ee61bb3" xlink:href="tw-20240630.xsd#tw_MarketDataRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:to="loc_tw_MarketDataRevenueMember_40d5b9b0-04fd-4604-a6fe-e5a48ee61bb3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialServiceOtherMember_d82f114f-75a4-4d0b-ad01-9c386be45495" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9cd8bad2-2573-48f8-9505-3205e5d6bef3" xlink:to="loc_us-gaap_FinancialServiceOtherMember_d82f114f-75a4-4d0b-ad01-9c386be45495" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_2eba676c-565f-4426-9800-735d5666a628" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_RevenuesAbstract_2eba676c-565f-4426-9800-735d5666a628" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_adfa99de-a81f-403c-8c6a-b2ab70f5018c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_2eba676c-565f-4426-9800-735d5666a628" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_adfa99de-a81f-403c-8c6a-b2ab70f5018c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_8b1e5d33-56b8-40f0-b7bc-2e83aa1c25ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_LaborAndRelatedExpense_8b1e5d33-56b8-40f0-b7bc-2e83aa1c25ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_be6ce9c3-359a-4559-982d-6e90b514440b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_DepreciationAndAmortization_be6ce9c3-359a-4559-982d-6e90b514440b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommunicationsAndInformationTechnology_67435ef9-13fa-47d0-a30f-52af7b56962a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommunicationsAndInformationTechnology"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_CommunicationsAndInformationTechnology_67435ef9-13fa-47d0-a30f-52af7b56962a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_183451fd-e699-4cb7-8106-771b82e4d090" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_183451fd-e699-4cb7-8106-771b82e4d090" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_31e40efd-02df-4435-bd1f-3bcdb8140e56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfessionalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_ProfessionalFees_31e40efd-02df-4435-bd1f-3bcdb8140e56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_524689a7-2381-45f1-a802-684210b01ba8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OccupancyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_OccupancyNet_524689a7-2381-45f1-a802-684210b01ba8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_fe335a9b-ef6a-48cb-bb92-30c786f45aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_bfd82b33-6062-485d-9584-4767491928f9" xlink:to="loc_us-gaap_CostsAndExpenses_fe335a9b-ef6a-48cb-bb92-30c786f45aa7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_233ce281-386b-4930-9de3-d007b6200e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_OperatingIncomeLoss_233ce281-386b-4930-9de3-d007b6200e7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterestAndDividend_bc53ffff-0095-4bd6-b1cb-b73e6ffbe43d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InvestmentIncomeInterestAndDividend"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_InvestmentIncomeInterestAndDividend_bc53ffff-0095-4bd6-b1cb-b73e6ffbe43d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_d1fcc28c-e72f-42eb-9b41-b7a75a3924ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_InterestExpenseNonoperating_d1fcc28c-e72f-42eb-9b41-b7a75a3924ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_d81c43a6-93cc-4b23-ab91-93e91e96fa1e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_d81c43a6-93cc-4b23-ab91-93e91e96fa1e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_cb733d2d-b527-4b5d-b708-d49ca8235c43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_cb733d2d-b527-4b5d-b708-d49ca8235c43" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_ff42f0af-12b2-4d7a-80ab-fa508263f738" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_ff42f0af-12b2-4d7a-80ab-fa508263f738" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_2d324f90-9606-44d0-8e0b-4e1733ba90b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_ProfitLoss_2d324f90-9606-44d0-8e0b-4e1733ba90b4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_12e9ca42-48fd-4b9d-999f-5fc477fc532a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_12e9ca42-48fd-4b9d-999f-5fc477fc532a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_cdc24440-807f-4503-985e-6b72b6384b62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_NetIncomeLoss_cdc24440-807f-4503-985e-6b72b6384b62" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_7665804e-a15b-4ee4-8de7-1fbca0786810" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_EarningsPerShareAbstract_7665804e-a15b-4ee4-8de7-1fbca0786810" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_1bc87729-5ea7-462f-a916-fc0017bd9ac0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7665804e-a15b-4ee4-8de7-1fbca0786810" xlink:to="loc_us-gaap_EarningsPerShareBasic_1bc87729-5ea7-462f-a916-fc0017bd9ac0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_6ea4b628-3a96-4585-afc4-2545fbb96c68" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7665804e-a15b-4ee4-8de7-1fbca0786810" xlink:to="loc_us-gaap_EarningsPerShareDiluted_6ea4b628-3a96-4585-afc4-2545fbb96c68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_70c00678-3df9-49c2-b946-8926b05cf258" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_60823644-51b2-42f8-8c5e-2448ff4e5803" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_70c00678-3df9-49c2-b946-8926b05cf258" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_fb2b253a-cc67-41f6-9fb9-cd06ea3fdca0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_70c00678-3df9-49c2-b946-8926b05cf258" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_fb2b253a-cc67-41f6-9fb9-cd06ea3fdca0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_83275698-fac0-4434-8433-de13e7a7b0d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_70c00678-3df9-49c2-b946-8926b05cf258" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_83275698-fac0-4434-8433-de13e7a7b0d3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofChangesinEquity" xlink:type="simple" xlink:href="tw-20240630.xsd#CondensedConsolidatedStatementsofChangesinEquity"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofChangesinEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_c64e8a4e-fa26-4b02-bbeb-df7312cb40c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_86c752b0-2fdc-4d8f-a851-c2e5b6af9e7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_c64e8a4e-fa26-4b02-bbeb-df7312cb40c1" xlink:to="loc_us-gaap_StatementTable_86c752b0-2fdc-4d8f-a851-c2e5b6af9e7d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_cb88380d-2687-42f5-b84e-00b301581848" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_86c752b0-2fdc-4d8f-a851-c2e5b6af9e7d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_cb88380d-2687-42f5-b84e-00b301581848" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_cb88380d-2687-42f5-b84e-00b301581848_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cb88380d-2687-42f5-b84e-00b301581848" xlink:to="loc_us-gaap_EquityComponentDomain_cb88380d-2687-42f5-b84e-00b301581848_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cb88380d-2687-42f5-b84e-00b301581848" xlink:to="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_b4e98888-ccdb-4c08-b58a-4e09a0140e17" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:to="loc_us-gaap_CommonStockMember_b4e98888-ccdb-4c08-b58a-4e09a0140e17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_9881b92f-563d-4c54-b575-f8313a7a22ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_9881b92f-563d-4c54-b575-f8313a7a22ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3762cc1f-582e-4f39-9f46-e05c811d7529" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3762cc1f-582e-4f39-9f46-e05c811d7529" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_dc316d9d-37f8-42d1-9120-d1e0f9c9cb7c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:to="loc_us-gaap_RetainedEarningsMember_dc316d9d-37f8-42d1-9120-d1e0f9c9cb7c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_1d58806e-e358-46ae-a3d6-c3d2908438b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e4d07a24-1a2f-46e4-95a3-bfc9f3908077" xlink:to="loc_us-gaap_NoncontrollingInterestMember_1d58806e-e358-46ae-a3d6-c3d2908438b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_fbefcec8-77ca-4ab4-a7f0-43af106186a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_86c752b0-2fdc-4d8f-a851-c2e5b6af9e7d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_fbefcec8-77ca-4ab4-a7f0-43af106186a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fbefcec8-77ca-4ab4-a7f0-43af106186a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fbefcec8-77ca-4ab4-a7f0-43af106186a4" xlink:to="loc_us-gaap_ClassOfStockDomain_fbefcec8-77ca-4ab4-a7f0-43af106186a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fbefcec8-77ca-4ab4-a7f0-43af106186a4" xlink:to="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_0acc6522-1680-4253-9dec-fe188ab64192" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:to="loc_us-gaap_CommonClassAMember_0acc6522-1680-4253-9dec-fe188ab64192" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_74a081ed-d9e8-4ef9-a381-c4ec0743aa98" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:to="loc_us-gaap_CommonClassBMember_74a081ed-d9e8-4ef9-a381-c4ec0743aa98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_1884ae6c-c164-4d01-b1c6-76c9983d0c94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:to="loc_us-gaap_CommonClassCMember_1884ae6c-c164-4d01-b1c6-76c9983d0c94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_7b508a0e-3969-4b4b-aa17-bf39879f1d6d" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ebd2f4f-1660-46d1-a0e4-25e14189e6f6" xlink:to="loc_tw_CommonClassDMember_7b508a0e-3969-4b4b-aa17-bf39879f1d6d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c64e8a4e-fa26-4b02-bbeb-df7312cb40c1" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_cd16e87d-009d-4717-b4fa-2429ea5c5e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_cd16e87d-009d-4717-b4fa-2429ea5c5e7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_31f930ea-5b00-4086-8577-e449a82017ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_31f930ea-5b00-4086-8577-e449a82017ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_81c2dc3d-8cc9-4f4f-81f8-66467938a993" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_81c2dc3d-8cc9-4f4f-81f8-66467938a993" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_c888fded-b71e-49d8-8ccd-68dc70d0801a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_c888fded-b71e-49d8-8ccd-68dc70d0801a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AdjustmentsToAdditionalPaidInCapitalTaxReceivableAgreementLiabilityAndDeferredTaxesReorganizationTransactionAndIpo_b0e6cdb0-2ae5-4ca5-b668-38dfcf776dfc" xlink:href="tw-20240630.xsd#tw_AdjustmentsToAdditionalPaidInCapitalTaxReceivableAgreementLiabilityAndDeferredTaxesReorganizationTransactionAndIpo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_tw_AdjustmentsToAdditionalPaidInCapitalTaxReceivableAgreementLiabilityAndDeferredTaxesReorganizationTransactionAndIpo_b0e6cdb0-2ae5-4ca5-b668-38dfcf776dfc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MinorityInterestIncreaseDecreaseFromAdjustments_786c5069-e931-481b-a1bb-04d38cf7c280" xlink:href="tw-20240630.xsd#tw_MinorityInterestIncreaseDecreaseFromAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_tw_MinorityInterestIncreaseDecreaseFromAdjustments_786c5069-e931-481b-a1bb-04d38cf7c280" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_5a4fed26-e963-4964-a5fd-58dc58e09c79" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_5a4fed26-e963-4964-a5fd-58dc58e09c79" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_1dc958be-bfd4-4df8-b34b-7cd6d71f7f29" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_Dividends_1dc958be-bfd4-4df8-b34b-7cd6d71f7f29" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_3eaa1f40-8cf5-4129-891e-1d8db3793c29" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_3eaa1f40-8cf5-4129-891e-1d8db3793c29" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_3510303f-89a8-46c1-b36c-af49ecd5e4d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_3510303f-89a8-46c1-b36c-af49ecd5e4d7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_a6891de6-5539-4b9f-b299-64ed43818be6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_ProfitLoss_a6891de6-5539-4b9f-b299-64ed43818be6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_90b5907b-ff46-4aeb-9008-d791eda670f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_92ebc190-29a0-48fb-92ef-86b5a12213ee" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_90b5907b-ff46-4aeb-9008-d791eda670f9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_edec994a-a3ba-41e5-a307-a7f03f4a50b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="tw-20240630.xsd#CondensedConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_5ba73fd3-7621-4027-9777-ce763ae0be9f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_StatementTable_5ba73fd3-7621-4027-9777-ce763ae0be9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_dd0e7217-9c6b-41c2-a577-7fa8328c95ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_5ba73fd3-7621-4027-9777-ce763ae0be9f" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_dd0e7217-9c6b-41c2-a577-7fa8328c95ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_dd0e7217-9c6b-41c2-a577-7fa8328c95ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_dd0e7217-9c6b-41c2-a577-7fa8328c95ad" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_dd0e7217-9c6b-41c2-a577-7fa8328c95ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_f933872d-d998-4832-ab2a-1d8e96ed6e19" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_dd0e7217-9c6b-41c2-a577-7fa8328c95ad" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_f933872d-d998-4832-ab2a-1d8e96ed6e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AdjustedForRefinitivTransactionMember_4e01c31a-0dd7-45eb-9f63-4384fdb4f3b7" xlink:href="tw-20240630.xsd#tw_AdjustedForRefinitivTransactionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_f933872d-d998-4832-ab2a-1d8e96ed6e19" xlink:to="loc_tw_AdjustedForRefinitivTransactionMember_4e01c31a-0dd7-45eb-9f63-4384fdb4f3b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_adb665c3-ecf5-4acf-9381-5f30636cccb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:to="loc_us-gaap_ProfitLoss_adb665c3-ecf5-4acf-9381-5f30636cccb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:to="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_e86fcccc-eb99-4403-a452-3e02a1ab445b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:to="loc_us-gaap_DepreciationAndAmortization_e86fcccc-eb99-4403-a452-3e02a1ab445b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_0d4a2dce-0160-4fc2-acfe-df6f17c70472" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:to="loc_us-gaap_ShareBasedCompensation_0d4a2dce-0160-4fc2-acfe-df6f17c70472" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_1362fe0b-3fd2-4790-a0a4-05f005111453" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_1362fe0b-3fd2-4790-a0a4-05f005111453" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_cda6491e-7df6-4e58-84fd-3aa1a5f02d7a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_cda6491e-7df6-4e58-84fd-3aa1a5f02d7a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOperatingAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_ec3ef085-5dd4-4503-9bdd-9b13fb2067b1" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInBrokerageReceivables_e161e1c5-4258-41a3-b2ec-3e30b1b0ed70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInBrokerageReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:to="loc_us-gaap_IncreaseDecreaseInBrokerageReceivables_e161e1c5-4258-41a3-b2ec-3e30b1b0ed70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets_52a1e6b9-510e-4ccb-aae1-d54ea7fa4cbf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInDepositOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:to="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets_52a1e6b9-510e-4ccb-aae1-d54ea7fa4cbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_a979dcd8-f2b0-4c1e-a594-ee55603bb048" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_a979dcd8-f2b0-4c1e-a594-ee55603bb048" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseDueFromAffiliates_1716964c-5947-448e-9d0d-b63a80546da7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseDueFromAffiliates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:to="loc_us-gaap_IncreaseDecreaseDueFromAffiliates_1716964c-5947-448e-9d0d-b63a80546da7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_def8c8a3-902d-46dd-9428-273e888835e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingAssetsAbstract_7c4c2dce-b011-4af7-9c30-50de4714ea54" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_def8c8a3-902d-46dd-9428-273e888835e7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInFinancialInstrumentsSoldNotYetPurchased_bbbc060a-7a10-4b61-a6ee-df03e1f6f256" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInFinancialInstrumentsSoldNotYetPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:to="loc_us-gaap_IncreaseDecreaseInFinancialInstrumentsSoldNotYetPurchased_bbbc060a-7a10-4b61-a6ee-df03e1f6f256" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_459bf1bb-3a39-4b34-9f9f-53fbda8f1e1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:to="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_459bf1bb-3a39-4b34-9f9f-53fbda8f1e1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_48454d79-5cb1-4416-b182-05032e36afd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_48454d79-5cb1-4416-b182-05032e36afd0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_213bac91-cf57-460f-bedc-e87346cbd7c6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract_713414ea-b707-406a-884e-4da52cfd4b3f" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_213bac91-cf57-460f-bedc-e87346cbd7c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_6893bc90-007f-492c-ba2b-636257f4d544" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c61e097c-b507-439b-9ccf-f8bf57551850" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_6893bc90-007f-492c-ba2b-636257f4d544" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_b4438a62-d3ee-42ac-8483-40282ef9dbed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_b4438a62-d3ee-42ac-8483-40282ef9dbed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_b60dc8ca-57f8-4891-afa4-841bf5340237" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_b60dc8ca-57f8-4891-afa4-841bf5340237" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireInvestments_13332d9e-e7a3-40ab-91a0-f80819f3ebbb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_PaymentsToAcquireInvestments_13332d9e-e7a3-40ab-91a0-f80819f3ebbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_542c8e2a-c4cc-412e-8886-f30255c6308a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_542c8e2a-c4cc-412e-8886-f30255c6308a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForSoftware_761abbc8-bf8a-45df-a21c-8022a1ac79e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForSoftware"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_PaymentsForSoftware_761abbc8-bf8a-45df-a21c-8022a1ac79e1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d326cd9c-e092-4045-98d8-5883caeae25e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_aaf3de53-799b-476b-9a57-ec2e5a97e79f" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d326cd9c-e092-4045-98d8-5883caeae25e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_4f3930c2-7bb4-445e-aade-aa99e5d57c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_4f3930c2-7bb4-445e-aade-aa99e5d57c9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_eb140aae-5f3c-4670-b0e6-8c5ffcd6b679" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_eb140aae-5f3c-4670-b0e6-8c5ffcd6b679" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfOrdinaryDividends_6189a4fa-d308-4a4c-b671-2d41d1ad7d27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfOrdinaryDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_us-gaap_PaymentsOfOrdinaryDividends_6189a4fa-d308-4a4c-b671-2d41d1ad7d27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_PaymentsOfCapitalDistributionToNoncontrollingInterest_b5666f4c-d54a-483e-aa56-901f5b54ad1a" xlink:href="tw-20240630.xsd#tw_PaymentsOfCapitalDistributionToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_tw_PaymentsOfCapitalDistributionToNoncontrollingInterest_b5666f4c-d54a-483e-aa56-901f5b54ad1a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_b1a07851-b970-4f1c-b374-ad6799f30e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_b1a07851-b970-4f1c-b374-ad6799f30e1a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_PaymentsOnTaxReceivableAgreementLiability_f1176fa1-de87-462b-ab73-08f246efbd54" xlink:href="tw-20240630.xsd#tw_PaymentsOnTaxReceivableAgreementLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_tw_PaymentsOnTaxReceivableAgreementLiability_f1176fa1-de87-462b-ab73-08f246efbd54" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_90c539e1-f1c8-4472-8e1d-8467f0175180" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1d00f1de-98c8-4ed3-a7b0-c3eb8ede5578" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_90c539e1-f1c8-4472-8e1d-8467f0175180" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_0c770f6c-5aec-4ba4-a81c-3ec2feee22e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_0c770f6c-5aec-4ba4-a81c-3ec2feee22e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_eb4a67b9-d704-4d79-8dcc-d36aeef1d3cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_eb4a67b9-d704-4d79-8dcc-d36aeef1d3cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract_8aad1590-6a36-47b5-ad2d-f330e2619596" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract_8aad1590-6a36-47b5-ad2d-f330e2619596" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_b1e8d6d5-c66d-4384-ad15-717b9ff29386" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract_8aad1590-6a36-47b5-ad2d-f330e2619596" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_b1e8d6d5-c66d-4384-ad15-717b9ff29386" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_284640de-4ccf-43f8-9dea-ed8fc4ecc00c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_993807e8-16a5-4909-9deb-5aade6c85a7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_993807e8-16a5-4909-9deb-5aade6c85a7f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_2b21c9cf-ca61-42ec-8318-4be568a0cb8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_993807e8-16a5-4909-9deb-5aade6c85a7f" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_2b21c9cf-ca61-42ec-8318-4be568a0cb8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_0a86cd32-105d-4e16-a912-bc3c5fe6a750" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_993807e8-16a5-4909-9deb-5aade6c85a7f" xlink:to="loc_us-gaap_InterestPaidNet_0a86cd32-105d-4e16-a912-bc3c5fe6a750" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssued1_2fb8c447-c55b-4f84-a64d-4ee2c3cd5dee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:to="loc_us-gaap_StockIssued1_2fb8c447-c55b-4f84-a64d-4ee2c3cd5dee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_c4e67c77-7f85-4b0d-bc0d-bb402a2e008e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_c4e67c77-7f85-4b0d-bc0d-bb402a2e008e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_UnsettledShareRepurchasesIncludedInOtherLiabilities_5b31c622-67cd-46d0-8546-07a5d360d028" xlink:href="tw-20240630.xsd#tw_UnsettledShareRepurchasesIncludedInOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:to="loc_tw_UnsettledShareRepurchasesIncludedInOtherLiabilities_5b31c622-67cd-46d0-8546-07a5d360d028" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAssumed1_59799a68-348b-44d0-91dd-3330054472d8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAssumed1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:to="loc_us-gaap_LiabilitiesAssumed1_59799a68-348b-44d0-91dd-3330054472d8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeTaxExpense_614b9973-d1ce-4801-b30d-1407f1d79a17" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNoncashIncomeTaxExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_b24992d8-f018-4fcd-975d-e5d699a96fef" xlink:to="loc_us-gaap_OtherNoncashIncomeTaxExpense_614b9973-d1ce-4801-b30d-1407f1d79a17" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalCashFlowElementsAndSupplementalCashFlowInformationAbstract_3a10dc47-551e-4137-b889-4db57cca7636" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalCashFlowElementsAndSupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61b2e2a3-67f5-414f-b08a-b91cb7f5f162" xlink:to="loc_us-gaap_AdditionalCashFlowElementsAndSupplementalCashFlowInformationAbstract_3a10dc47-551e-4137-b889-4db57cca7636" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_c6ebdfdf-fe3d-46a8-8fd4-18bb037ccf95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalCashFlowElementsAndSupplementalCashFlowInformationAbstract_3a10dc47-551e-4137-b889-4db57cca7636" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_c6ebdfdf-fe3d-46a8-8fd4-18bb037ccf95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_88ad91db-223d-45ab-a5a4-03f705e7bdb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalCashFlowElementsAndSupplementalCashFlowInformationAbstract_3a10dc47-551e-4137-b889-4db57cca7636" xlink:to="loc_us-gaap_RestrictedCash_88ad91db-223d-45ab-a5a4-03f705e7bdb8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bf3a7347-7916-469e-91ce-b26f60ddd8fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/OrganizationDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#OrganizationDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/OrganizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_ac552397-5762-4536-af08-0c0e7553f42c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:to="loc_srt_OwnershipAxis_ac552397-5762-4536-af08-0c0e7553f42c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_ac552397-5762-4536-af08-0c0e7553f42c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_ac552397-5762-4536-af08-0c0e7553f42c" xlink:to="loc_srt_OwnershipDomain_ac552397-5762-4536-af08-0c0e7553f42c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_18d240e6-76c2-46bb-9a4b-ed8aea4abc8b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_ac552397-5762-4536-af08-0c0e7553f42c" xlink:to="loc_srt_OwnershipDomain_18d240e6-76c2-46bb-9a4b-ed8aea4abc8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebMarketsLLCMember_85aa8ac1-f787-40fa-8454-fd683acf681f" xlink:href="tw-20240630.xsd#tw_TradewebMarketsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_18d240e6-76c2-46bb-9a4b-ed8aea4abc8b" xlink:to="loc_tw_TradewebMarketsLLCMember_85aa8ac1-f787-40fa-8454-fd683acf681f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebMarketsIncMember_f0acf798-5084-4458-a8e5-d6a5e88cee2d" xlink:href="tw-20240630.xsd#tw_TradewebMarketsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_18d240e6-76c2-46bb-9a4b-ed8aea4abc8b" xlink:to="loc_tw_TradewebMarketsIncMember_f0acf798-5084-4458-a8e5-d6a5e88cee2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_c9d10292-7c18-4c36-8a9e-902a8f54206f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_c9d10292-7c18-4c36-8a9e-902a8f54206f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c9d10292-7c18-4c36-8a9e-902a8f54206f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c9d10292-7c18-4c36-8a9e-902a8f54206f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c9d10292-7c18-4c36-8a9e-902a8f54206f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cf404132-b9ad-41cb-8c0d-46661037aa51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c9d10292-7c18-4c36-8a9e-902a8f54206f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cf404132-b9ad-41cb-8c0d-46661037aa51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_R8FinMember_3dbfcd56-8944-47ba-807f-7c80d3236b24" xlink:href="tw-20240630.xsd#tw_R8FinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cf404132-b9ad-41cb-8c0d-46661037aa51" xlink:to="loc_tw_R8FinMember_3dbfcd56-8944-47ba-807f-7c80d3236b24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_YieldbrokerMember_73db3ac9-9ad0-4232-8a7f-d45b649adede" xlink:href="tw-20240630.xsd#tw_YieldbrokerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cf404132-b9ad-41cb-8c0d-46661037aa51" xlink:to="loc_tw_YieldbrokerMember_73db3ac9-9ad0-4232-8a7f-d45b649adede" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_1181a4cb-af26-419a-bed1-1c822e0df4f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:to="loc_us-gaap_StatementClassOfStockAxis_1181a4cb-af26-419a-bed1-1c822e0df4f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1181a4cb-af26-419a-bed1-1c822e0df4f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1181a4cb-af26-419a-bed1-1c822e0df4f5" xlink:to="loc_us-gaap_ClassOfStockDomain_1181a4cb-af26-419a-bed1-1c822e0df4f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1181a4cb-af26-419a-bed1-1c822e0df4f5" xlink:to="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_88744c17-5c33-4af8-9770-1aaade5f977c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:to="loc_us-gaap_CommonClassAMember_88744c17-5c33-4af8-9770-1aaade5f977c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_b7cf21d5-56ef-42a8-8582-e30e2af95c72" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:to="loc_us-gaap_CommonClassBMember_b7cf21d5-56ef-42a8-8582-e30e2af95c72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_12f97024-c3b2-4df5-a002-99833e2d3342" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:to="loc_us-gaap_CommonClassCMember_12f97024-c3b2-4df5-a002-99833e2d3342" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_e9b0db46-f0d8-4f6a-803a-dab4bafb8294" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c087e733-82a8-4800-9047-d6e6f32e6679" xlink:to="loc_tw_CommonClassDMember_e9b0db46-f0d8-4f6a-803a-dab4bafb8294" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_bdfd9000-8032-4479-9f51-f575e298d5ab" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:to="loc_srt_TitleOfIndividualAxis_bdfd9000-8032-4479-9f51-f575e298d5ab" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_bdfd9000-8032-4479-9f51-f575e298d5ab_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_bdfd9000-8032-4479-9f51-f575e298d5ab" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_bdfd9000-8032-4479-9f51-f575e298d5ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d38e1297-0b0a-4662-89b4-c0b2b3573b67" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_bdfd9000-8032-4479-9f51-f575e298d5ab" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d38e1297-0b0a-4662-89b4-c0b2b3573b67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_PublicInvestorsMember_be302912-cb77-473e-b457-e99e850cb3b4" xlink:href="tw-20240630.xsd#tw_PublicInvestorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d38e1297-0b0a-4662-89b4-c0b2b3573b67" xlink:to="loc_tw_PublicInvestorsMember_be302912-cb77-473e-b457-e99e850cb3b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_OtherStockholdersMember_91c697ac-39d7-4dff-94f1-997d8b47db2f" xlink:href="tw-20240630.xsd#tw_OtherStockholdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d38e1297-0b0a-4662-89b4-c0b2b3573b67" xlink:to="loc_tw_OtherStockholdersMember_91c697ac-39d7-4dff-94f1-997d8b47db2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_f04c1160-fdea-41c0-9212-cc46be761c4d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable_fd8ae8c5-ce44-4e9a-a7ad-de1c9d789cca" xlink:to="loc_dei_LegalEntityAxis_f04c1160-fdea-41c0-9212-cc46be761c4d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_f04c1160-fdea-41c0-9212-cc46be761c4d_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_f04c1160-fdea-41c0-9212-cc46be761c4d" xlink:to="loc_dei_EntityDomain_f04c1160-fdea-41c0-9212-cc46be761c4d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7e1cfee4-f5c6-48fb-a653-cbbc8b32acea" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_f04c1160-fdea-41c0-9212-cc46be761c4d" xlink:to="loc_dei_EntityDomain_7e1cfee4-f5c6-48fb-a653-cbbc8b32acea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RefinitivMember_cda785b3-a2d5-471c-ba86-6bc990bca95c" xlink:href="tw-20240630.xsd#tw_RefinitivMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7e1cfee4-f5c6-48fb-a653-cbbc8b32acea" xlink:to="loc_tw_RefinitivMember_cda785b3-a2d5-471c-ba86-6bc990bca95c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_a2d3e6cc-a669-4905-b56a-d398d0264035" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_a2d3e6cc-a669-4905-b56a-d398d0264035" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_8d13e85c-2de3-48af-8f80-b2af4b64ec89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_8d13e85c-2de3-48af-8f80-b2af4b64ec89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_547fec16-1bd5-45db-8ba5-c24b22ce3ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_547fec16-1bd5-45db-8ba5-c24b22ce3ebb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_4d9f1472-6976-43aa-8cce-2bdebf45ca8b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_4d9f1472-6976-43aa-8cce-2bdebf45ca8b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_77dd401c-4009-4ad1-9af6-3254e7e3267e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_77dd401c-4009-4ad1-9af6-3254e7e3267e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_NumberOfShareOwned_6cea1c3c-4e67-4299-bde1-fb12f44e48d9" xlink:href="tw-20240630.xsd#tw_NumberOfShareOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_tw_NumberOfShareOwned_6cea1c3c-4e67-4299-bde1-fb12f44e48d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_VotingPowerPercentage_9f863da1-b043-4a89-b9f0-214abd55a498" xlink:href="tw-20240630.xsd#tw_VotingPowerPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_tw_VotingPowerPercentage_9f863da1-b043-4a89-b9f0-214abd55a498" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares_d217de22-869b-44d6-97c7-0e21bfa0fd87" xlink:href="tw-20240630.xsd#tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares_d217de22-869b-44d6-97c7-0e21bfa0fd87" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_c4787c77-3355-4885-b771-390a3907dba9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems_8981d17e-56e3-4f33-b7c7-e2911f430123" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_c4787c77-3355-4885-b771-390a3907dba9" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/SignificantAccountingPoliciesFurnitureEquipmentPurchasedSoftwareLeaseholdImprovementsandSoftwareDevelopmentCostDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#SignificantAccountingPoliciesFurnitureEquipmentPurchasedSoftwareLeaseholdImprovementsandSoftwareDevelopmentCostDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/SignificantAccountingPoliciesFurnitureEquipmentPurchasedSoftwareLeaseholdImprovementsandSoftwareDevelopmentCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_204746fa-e3d5-4a03-a06f-ccfd5f27069c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_204746fa-e3d5-4a03-a06f-ccfd5f27069c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_204746fa-e3d5-4a03-a06f-ccfd5f27069c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_204746fa-e3d5-4a03-a06f-ccfd5f27069c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_204746fa-e3d5-4a03-a06f-ccfd5f27069c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_03a2aa43-6cd3-4aa5-8f75-6e6332202c6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_204746fa-e3d5-4a03-a06f-ccfd5f27069c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_03a2aa43-6cd3-4aa5-8f75-6e6332202c6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_FurnitureEquipmentAndPurchasedSoftwareMember_89852b75-1f01-4f1e-bddb-a66993b16b8f" xlink:href="tw-20240630.xsd#tw_FurnitureEquipmentAndPurchasedSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_03a2aa43-6cd3-4aa5-8f75-6e6332202c6c" xlink:to="loc_tw_FurnitureEquipmentAndPurchasedSoftwareMember_89852b75-1f01-4f1e-bddb-a66993b16b8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_724ac444-22ce-49d4-80b3-ae3e50fe6786" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:to="loc_srt_RangeAxis_724ac444-22ce-49d4-80b3-ae3e50fe6786" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_724ac444-22ce-49d4-80b3-ae3e50fe6786_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_724ac444-22ce-49d4-80b3-ae3e50fe6786" xlink:to="loc_srt_RangeMember_724ac444-22ce-49d4-80b3-ae3e50fe6786_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3ec61370-6c57-48c8-841b-e5fd434b2732" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_724ac444-22ce-49d4-80b3-ae3e50fe6786" xlink:to="loc_srt_RangeMember_3ec61370-6c57-48c8-841b-e5fd434b2732" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f95e4673-3bbd-4f94-a68c-0d3e1e24b55a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3ec61370-6c57-48c8-841b-e5fd434b2732" xlink:to="loc_srt_MinimumMember_f95e4673-3bbd-4f94-a68c-0d3e1e24b55a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5c0a1eec-510e-4f33-9d45-632dd5c8741e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3ec61370-6c57-48c8-841b-e5fd434b2732" xlink:to="loc_srt_MaximumMember_5c0a1eec-510e-4f33-9d45-632dd5c8741e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_5671d8c5-11c6-4fca-becd-c5c1bc958ce7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_5671d8c5-11c6-4fca-becd-c5c1bc958ce7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5671d8c5-11c6-4fca-becd-c5c1bc958ce7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_5671d8c5-11c6-4fca-becd-c5c1bc958ce7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5671d8c5-11c6-4fca-becd-c5c1bc958ce7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6534838a-6122-4afc-976b-f33e51016714" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_5671d8c5-11c6-4fca-becd-c5c1bc958ce7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6534838a-6122-4afc-976b-f33e51016714" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_f9273b77-0766-4613-a9fc-e8f699e0c951" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6534838a-6122-4afc-976b-f33e51016714" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_f9273b77-0766-4613-a9fc-e8f699e0c951" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_b0d991c9-c457-4050-86b3-e213449f2dad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_c4772e55-7eee-4d5c-988e-2c6bb5f2e18a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_b0d991c9-c457-4050-86b3-e213449f2dad" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b0d991c9-c457-4050-86b3-e213449f2dad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b0d991c9-c457-4050-86b3-e213449f2dad" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b0d991c9-c457-4050-86b3-e213449f2dad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1ba211f8-7458-45a5-abd7-a586d9530ba6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b0d991c9-c457-4050-86b3-e213449f2dad" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1ba211f8-7458-45a5-abd7-a586d9530ba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_R8FinMember_7fe8291f-abe4-4b11-a812-1c96de94c7ca" xlink:href="tw-20240630.xsd#tw_R8FinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1ba211f8-7458-45a5-abd7-a586d9530ba6" xlink:to="loc_tw_R8FinMember_7fe8291f-abe4-4b11-a812-1c96de94c7ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_YieldbrokerAcquisitionMember_31999ddb-a8ff-4de8-b5ad-1188e9557063" xlink:href="tw-20240630.xsd#tw_YieldbrokerAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1ba211f8-7458-45a5-abd7-a586d9530ba6" xlink:to="loc_tw_YieldbrokerAcquisitionMember_31999ddb-a8ff-4de8-b5ad-1188e9557063" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_NFIAcquisitionMember_fc798399-af19-432e-b790-52365d565764" xlink:href="tw-20240630.xsd#tw_NFIAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1ba211f8-7458-45a5-abd7-a586d9530ba6" xlink:to="loc_tw_NFIAcquisitionMember_fc798399-af19-432e-b790-52365d565764" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_a2c092d8-7bb7-42a3-bdc9-e789f57cb290" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_a2c092d8-7bb7-42a3-bdc9-e789f57cb290" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_c2dd1da5-8fa4-4c9c-b625-c4a1db156f14" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_c2dd1da5-8fa4-4c9c-b625-c4a1db156f14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_088d6280-097e-4865-be7c-5e040883e429" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_Depreciation_088d6280-097e-4865-be7c-5e040883e429" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_aa0b1fd3-308a-42d6-bc4e-dc6d2f66298d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_aa0b1fd3-308a-42d6-bc4e-dc6d2f66298d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AmortizationPeriodPushdownAccountingAdjustment_8e5c6011-c6d2-4a57-878a-b223eddd0c14" xlink:href="tw-20240630.xsd#tw_AmortizationPeriodPushdownAccountingAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_tw_AmortizationPeriodPushdownAccountingAdjustment_8e5c6011-c6d2-4a57-878a-b223eddd0c14" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_ca9f7a0e-d1ae-475c-b503-0fe5a304f4c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b177efb5-70c7-4e11-a6e0-9c3e46e40811" xlink:to="loc_us-gaap_AdjustmentForAmortization_ca9f7a0e-d1ae-475c-b503-0fe5a304f4c1" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/SignificantAccountingPoliciesIntangibleAssetsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#SignificantAccountingPoliciesIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/SignificantAccountingPoliciesIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_061aee4b-c960-4a44-a01f-d18d95e00032" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_2e7f60fa-21ce-4fa6-be48-239495ac17b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_061aee4b-c960-4a44-a01f-d18d95e00032" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_2e7f60fa-21ce-4fa6-be48-239495ac17b5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ec662323-9f36-412d-8ceb-e2efee63bc62" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_2e7f60fa-21ce-4fa6-be48-239495ac17b5" xlink:to="loc_srt_RangeAxis_ec662323-9f36-412d-8ceb-e2efee63bc62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ec662323-9f36-412d-8ceb-e2efee63bc62_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ec662323-9f36-412d-8ceb-e2efee63bc62" xlink:to="loc_srt_RangeMember_ec662323-9f36-412d-8ceb-e2efee63bc62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3568de52-b8e2-4a8d-87b6-e691c22a422d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ec662323-9f36-412d-8ceb-e2efee63bc62" xlink:to="loc_srt_RangeMember_3568de52-b8e2-4a8d-87b6-e691c22a422d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_9b07b0f1-e1eb-4a02-9843-868be80c453c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3568de52-b8e2-4a8d-87b6-e691c22a422d" xlink:to="loc_srt_MinimumMember_9b07b0f1-e1eb-4a02-9843-868be80c453c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6f7112e8-1447-44a8-a3f9-f86912a091d0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3568de52-b8e2-4a8d-87b6-e691c22a422d" xlink:to="loc_srt_MaximumMember_6f7112e8-1447-44a8-a3f9-f86912a091d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_807f3133-92f3-43ff-be4a-cf0d4e4fbc6d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_061aee4b-c960-4a44-a01f-d18d95e00032" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_807f3133-92f3-43ff-be4a-cf0d4e4fbc6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_325f634b-784b-4214-b5ee-8153172df8f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_061aee4b-c960-4a44-a01f-d18d95e00032" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_325f634b-784b-4214-b5ee-8153172df8f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_4f9c746f-7458-4d61-803e-4b6318001884" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_061aee4b-c960-4a44-a01f-d18d95e00032" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_4f9c746f-7458-4d61-803e-4b6318001884" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/SignificantAccountingPoliciesTranslationofForeignCurrencyandExchangeDerivativeContractsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#SignificantAccountingPoliciesTranslationofForeignCurrencyandExchangeDerivativeContractsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/SignificantAccountingPoliciesTranslationofForeignCurrencyandExchangeDerivativeContractsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_0ea5ef78-a5df-460f-ab92-4cd5910617e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_72c94d33-1186-4cb2-8c02-afc640cf36ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_0ea5ef78-a5df-460f-ab92-4cd5910617e9" xlink:to="loc_us-gaap_DerivativeTable_72c94d33-1186-4cb2-8c02-afc640cf36ec" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_184e623f-e325-46aa-86a5-96cec040a126" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_72c94d33-1186-4cb2-8c02-afc640cf36ec" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_184e623f-e325-46aa-86a5-96cec040a126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_184e623f-e325-46aa-86a5-96cec040a126_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_184e623f-e325-46aa-86a5-96cec040a126" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_184e623f-e325-46aa-86a5-96cec040a126_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1c2a9c8c-71e6-472d-b4eb-d26f0bc742f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_184e623f-e325-46aa-86a5-96cec040a126" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1c2a9c8c-71e6-472d-b4eb-d26f0bc742f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_746e244a-d866-49b3-803b-1632b95ebca8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1c2a9c8c-71e6-472d-b4eb-d26f0bc742f5" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_746e244a-d866-49b3-803b-1632b95ebca8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeOptionMember_a7a4c4ef-389c-491f-a759-9a9f376bd51a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1c2a9c8c-71e6-472d-b4eb-d26f0bc742f5" xlink:to="loc_us-gaap_ForeignExchangeOptionMember_a7a4c4ef-389c-491f-a759-9a9f376bd51a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_390998f2-b4f4-4775-bc7e-8b8f832e108e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_72c94d33-1186-4cb2-8c02-afc640cf36ec" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_390998f2-b4f4-4775-bc7e-8b8f832e108e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_390998f2-b4f4-4775-bc7e-8b8f832e108e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_390998f2-b4f4-4775-bc7e-8b8f832e108e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_390998f2-b4f4-4775-bc7e-8b8f832e108e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_b550534e-5ffa-4cc1-bd42-82c7bccb4d43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_390998f2-b4f4-4775-bc7e-8b8f832e108e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_b550534e-5ffa-4cc1-bd42-82c7bccb4d43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_dc3825d7-7217-4028-933f-9bbfe126ca96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_b550534e-5ffa-4cc1-bd42-82c7bccb4d43" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_dc3825d7-7217-4028-933f-9bbfe126ca96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_3430be4d-d0c7-4045-bdb7-88aaa2eae612" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0ea5ef78-a5df-460f-ab92-4cd5910617e9" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_3430be4d-d0c7-4045-bdb7-88aaa2eae612" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_93e901fc-80ce-4234-8276-6ca6c5d73116" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0ea5ef78-a5df-460f-ab92-4cd5910617e9" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_93e901fc-80ce-4234-8276-6ca6c5d73116" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/AcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#AcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3130450a-3cd9-4c9b-a984-49b8a626fa07" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3130450a-3cd9-4c9b-a984-49b8a626fa07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3130450a-3cd9-4c9b-a984-49b8a626fa07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3130450a-3cd9-4c9b-a984-49b8a626fa07" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3130450a-3cd9-4c9b-a984-49b8a626fa07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1281fd85-96dd-4d2f-bb11-03c1650adf39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3130450a-3cd9-4c9b-a984-49b8a626fa07" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1281fd85-96dd-4d2f-bb11-03c1650adf39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_R8FinMember_ee72cd12-d5a4-4533-9b0d-798d0abc7d0e" xlink:href="tw-20240630.xsd#tw_R8FinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1281fd85-96dd-4d2f-bb11-03c1650adf39" xlink:to="loc_tw_R8FinMember_ee72cd12-d5a4-4533-9b0d-798d0abc7d0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ICDMember_6cdbadde-0934-49c3-ae9d-9df1af9438b4" xlink:href="tw-20240630.xsd#tw_ICDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1281fd85-96dd-4d2f-bb11-03c1650adf39" xlink:to="loc_tw_ICDMember_6cdbadde-0934-49c3-ae9d-9df1af9438b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_40e08059-6b09-4a10-9f9d-24718402e371" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_40e08059-6b09-4a10-9f9d-24718402e371" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_40e08059-6b09-4a10-9f9d-24718402e371_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_40e08059-6b09-4a10-9f9d-24718402e371" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_40e08059-6b09-4a10-9f9d-24718402e371_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5f60f1c3-64f0-4a9a-b097-5d9d9226609b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_40e08059-6b09-4a10-9f9d-24718402e371" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5f60f1c3-64f0-4a9a-b097-5d9d9226609b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_5368b9eb-6eb4-4ea2-9009-c36af8128996" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5f60f1c3-64f0-4a9a-b097-5d9d9226609b" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_5368b9eb-6eb4-4ea2-9009-c36af8128996" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_f86f2486-5613-42da-9ddf-498aee02bb31" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5f60f1c3-64f0-4a9a-b097-5d9d9226609b" xlink:to="loc_us-gaap_CustomerRelationshipsMember_f86f2486-5613-42da-9ddf-498aee02bb31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_335b4190-fb76-48e3-9ece-72921edbaad0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_335b4190-fb76-48e3-9ece-72921edbaad0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_335b4190-fb76-48e3-9ece-72921edbaad0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_335b4190-fb76-48e3-9ece-72921edbaad0" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_335b4190-fb76-48e3-9ece-72921edbaad0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ac568410-f095-4255-93d8-151cfc6fe13f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_335b4190-fb76-48e3-9ece-72921edbaad0" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ac568410-f095-4255-93d8-151cfc6fe13f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ProfessionalFeesMember_9ab34fec-6023-4dcf-ac2f-341db4161377" xlink:href="tw-20240630.xsd#tw_ProfessionalFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ac568410-f095-4255-93d8-151cfc6fe13f" xlink:to="loc_tw_ProfessionalFeesMember_9ab34fec-6023-4dcf-ac2f-341db4161377" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_09286489-9e82-4d22-a639-a28e314b7eee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ac568410-f095-4255-93d8-151cfc6fe13f" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_09286489-9e82-4d22-a639-a28e314b7eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2bcb7b96-9687-44dc-b67f-c99ad512216b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ad03f291-7749-4e82-968e-58f32e81f0ea" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2bcb7b96-9687-44dc-b67f-c99ad512216b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_2bcb7b96-9687-44dc-b67f-c99ad512216b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2bcb7b96-9687-44dc-b67f-c99ad512216b" xlink:to="loc_us-gaap_ClassOfStockDomain_2bcb7b96-9687-44dc-b67f-c99ad512216b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_677ac445-3afb-4786-a7b2-c8eef289186e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2bcb7b96-9687-44dc-b67f-c99ad512216b" xlink:to="loc_us-gaap_ClassOfStockDomain_677ac445-3afb-4786-a7b2-c8eef289186e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_0c89e1d3-76bb-4d2f-b938-34f052c2ddba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_677ac445-3afb-4786-a7b2-c8eef289186e" xlink:to="loc_us-gaap_CommonClassAMember_0c89e1d3-76bb-4d2f-b938-34f052c2ddba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_592d9973-f943-46f5-82f3-3c0a7fc3b338" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_592d9973-f943-46f5-82f3-3c0a7fc3b338" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_cb7c2af2-7857-4c73-8706-262fc98c4242" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_cb7c2af2-7857-4c73-8706-262fc98c4242" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_8de9c9ae-360c-4991-a35b-9fa25e2e29a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_8de9c9ae-360c-4991-a35b-9fa25e2e29a8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_a343d7fb-ab10-49f2-8608-f4b33ff1bdf9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_a343d7fb-ab10-49f2-8608-f4b33ff1bdf9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_d6a9a147-bfba-42ec-90c2-c59d92ad63d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_d6a9a147-bfba-42ec-90c2-c59d92ad63d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_0fcc2620-d2ed-4d3a-a5b4-01c89ffa29c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_0fcc2620-d2ed-4d3a-a5b4-01c89ffa29c1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_39dd0071-50c6-4074-8eed-956e518f76df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12265430-43b1-4e21-9a2b-aa8f2fc021b5" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_39dd0071-50c6-4074-8eed-956e518f76df" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/AcquisitionsScheduleofFinalPurchasePriceDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#AcquisitionsScheduleofFinalPurchasePriceDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/AcquisitionsScheduleofFinalPurchasePriceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_330dd71f-641f-406b-94fa-4087f4c7bcf1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_48cc161e-ad2b-4941-9aa1-206b820734e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_330dd71f-641f-406b-94fa-4087f4c7bcf1" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_48cc161e-ad2b-4941-9aa1-206b820734e4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_33824c23-86ef-46ec-9eaa-06a4a52c69e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_48cc161e-ad2b-4941-9aa1-206b820734e4" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_33824c23-86ef-46ec-9eaa-06a4a52c69e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_33824c23-86ef-46ec-9eaa-06a4a52c69e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_33824c23-86ef-46ec-9eaa-06a4a52c69e2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_33824c23-86ef-46ec-9eaa-06a4a52c69e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b32c7745-700f-4d27-bf82-d428d1a2c2d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_33824c23-86ef-46ec-9eaa-06a4a52c69e2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b32c7745-700f-4d27-bf82-d428d1a2c2d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_R8FinMember_5426572b-053d-4be9-a32b-372915adcd84" xlink:href="tw-20240630.xsd#tw_R8FinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b32c7745-700f-4d27-bf82-d428d1a2c2d6" xlink:to="loc_tw_R8FinMember_5426572b-053d-4be9-a32b-372915adcd84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3c5b315d-68f3-4d26-9c35-1589d47be5a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_48cc161e-ad2b-4941-9aa1-206b820734e4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3c5b315d-68f3-4d26-9c35-1589d47be5a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3c5b315d-68f3-4d26-9c35-1589d47be5a6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3c5b315d-68f3-4d26-9c35-1589d47be5a6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3c5b315d-68f3-4d26-9c35-1589d47be5a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_54f81be6-741c-4799-8e54-629b39589370" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3c5b315d-68f3-4d26-9c35-1589d47be5a6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_54f81be6-741c-4799-8e54-629b39589370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_022da1f2-f94d-4476-9272-8c3ae0b8be99" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_54f81be6-741c-4799-8e54-629b39589370" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_022da1f2-f94d-4476-9272-8c3ae0b8be99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_8040c948-2ad8-48e6-af0b-7d51ddb23fec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_54f81be6-741c-4799-8e54-629b39589370" xlink:to="loc_us-gaap_CustomerRelationshipsMember_8040c948-2ad8-48e6-af0b-7d51ddb23fec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_330dd71f-641f-406b-94fa-4087f4c7bcf1" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_11f4956f-a118-41f1-b43a-bf5ac488bc08" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_11f4956f-a118-41f1-b43a-bf5ac488bc08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_d7d226f5-cef8-47c6-8ead-f1bfebaa59e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_d7d226f5-cef8-47c6-8ead-f1bfebaa59e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_82ccd363-5d60-46cd-bf17-04919418f31f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_82ccd363-5d60-46cd-bf17-04919418f31f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_989dbede-d827-4af1-8f85-77bb11f46b69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_Goodwill_989dbede-d827-4af1-8f85-77bb11f46b69" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_b11beae5-bfe8-428e-9490-c842c40477d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_b11beae5-bfe8-428e-9490-c842c40477d4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_1a0221e7-b88c-4700-b4c5-aa62ebb59ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_1a0221e7-b88c-4700-b4c5-aa62ebb59ee8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_26d1d080-c266-410c-b635-36d8e53923bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_26d1d080-c266-410c-b635-36d8e53923bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_4d1d1ad3-abff-4fd0-8eee-baaf53019f08" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_4d1d1ad3-abff-4fd0-8eee-baaf53019f08" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_8ed29d32-40e5-40bb-9342-662d7337d6f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_11bc8457-226f-4bd0-b4cb-41e53946bcc9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_11bc8457-226f-4bd0-b4cb-41e53946bcc9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_4af3d03c-6b0f-4840-b974-4e2395b6b922" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_3ffcce9e-b798-45fd-9824-4b3500225fd6" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_4af3d03c-6b0f-4840-b974-4e2395b6b922" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/RevenueScheduleofBreakdownofRevenuesBetweenFixedandVariableRevenuesDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#RevenueScheduleofBreakdownofRevenuesBetweenFixedandVariableRevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/RevenueScheduleofBreakdownofRevenuesBetweenFixedandVariableRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_178b86e5-bf28-4e77-be12-87126d63cbe8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_adcf65d3-d366-4718-aa28-ef8f3d26499b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_178b86e5-bf28-4e77-be12-87126d63cbe8" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_adcf65d3-d366-4718-aa28-ef8f3d26499b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_3a1713f7-e139-46cb-91ce-ceefc3d7e68c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_adcf65d3-d366-4718-aa28-ef8f3d26499b" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_3a1713f7-e139-46cb-91ce-ceefc3d7e68c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_3a1713f7-e139-46cb-91ce-ceefc3d7e68c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_3a1713f7-e139-46cb-91ce-ceefc3d7e68c" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_3a1713f7-e139-46cb-91ce-ceefc3d7e68c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_93ea5feb-4a2a-4d16-bb58-11f4050d39a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_3a1713f7-e139-46cb-91ce-ceefc3d7e68c" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_93ea5feb-4a2a-4d16-bb58-11f4050d39a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_VariablePricingMember_50f569c7-ac90-478a-9bfb-758727619432" xlink:href="tw-20240630.xsd#tw_VariablePricingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_93ea5feb-4a2a-4d16-bb58-11f4050d39a6" xlink:to="loc_tw_VariablePricingMember_50f569c7-ac90-478a-9bfb-758727619432" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_195061bb-8a55-43db-8397-63cfae5dead6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_93ea5feb-4a2a-4d16-bb58-11f4050d39a6" xlink:to="loc_us-gaap_FixedPriceContractMember_195061bb-8a55-43db-8397-63cfae5dead6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_7e19ba98-76da-43cd-8070-fc59a2834ed1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_adcf65d3-d366-4718-aa28-ef8f3d26499b" xlink:to="loc_srt_ProductOrServiceAxis_7e19ba98-76da-43cd-8070-fc59a2834ed1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_7e19ba98-76da-43cd-8070-fc59a2834ed1_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_7e19ba98-76da-43cd-8070-fc59a2834ed1" xlink:to="loc_srt_ProductsAndServicesDomain_7e19ba98-76da-43cd-8070-fc59a2834ed1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_7e19ba98-76da-43cd-8070-fc59a2834ed1" xlink:to="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TransactionFeeRevenueMember_84ea98b9-a06e-4299-a730-20b17186a347" xlink:href="tw-20240630.xsd#tw_TransactionFeeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:to="loc_tw_TransactionFeeRevenueMember_84ea98b9-a06e-4299-a730-20b17186a347" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_SubscriptionFeeAndMarketDataRevenueMember_c88b2422-bdbc-4b82-a102-0dda66b68aef" xlink:href="tw-20240630.xsd#tw_SubscriptionFeeAndMarketDataRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:to="loc_tw_SubscriptionFeeAndMarketDataRevenueMember_c88b2422-bdbc-4b82-a102-0dda66b68aef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MarketDataRevenueMember_76d95aa4-aacb-432b-af83-43d99f8326b6" xlink:href="tw-20240630.xsd#tw_MarketDataRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:to="loc_tw_MarketDataRevenueMember_76d95aa4-aacb-432b-af83-43d99f8326b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialServiceOtherMember_48c20300-873e-4013-a475-9a91a9064a1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d6849b28-fd61-4ac1-9715-7506b6f594c0" xlink:to="loc_us-gaap_FinancialServiceOtherMember_48c20300-873e-4013-a475-9a91a9064a1c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueAbstract_fc2b99eb-eaf5-4b14-8d83-327a4ce27700" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_178b86e5-bf28-4e77-be12-87126d63cbe8" xlink:to="loc_us-gaap_DisaggregationOfRevenueAbstract_fc2b99eb-eaf5-4b14-8d83-327a4ce27700" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_217cc9e4-6f3f-4fc4-b55c-51b70cbb79ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueAbstract_fc2b99eb-eaf5-4b14-8d83-327a4ce27700" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_217cc9e4-6f3f-4fc4-b55c-51b70cbb79ee" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:href="tw-20240630.xsd#tw_IncomeTaxDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_IncomeTaxDisclosureTable_744908f5-bab9-4596-8014-539d92d77d7c" xlink:href="tw-20240630.xsd#tw_IncomeTaxDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_tw_IncomeTaxDisclosureTable_744908f5-bab9-4596-8014-539d92d77d7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_2c696427-6058-41b2-b26c-71e6cc789e63" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tw_IncomeTaxDisclosureTable_744908f5-bab9-4596-8014-539d92d77d7c" xlink:to="loc_dei_LegalEntityAxis_2c696427-6058-41b2-b26c-71e6cc789e63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_2c696427-6058-41b2-b26c-71e6cc789e63_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_2c696427-6058-41b2-b26c-71e6cc789e63" xlink:to="loc_dei_EntityDomain_2c696427-6058-41b2-b26c-71e6cc789e63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_78c18456-237d-414c-a36b-529fb8aeaebc" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_2c696427-6058-41b2-b26c-71e6cc789e63" xlink:to="loc_dei_EntityDomain_78c18456-237d-414c-a36b-529fb8aeaebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RefinitivDirectOwnerMember_74498aef-bf8c-4b6e-9f99-cd79893fc023" xlink:href="tw-20240630.xsd#tw_RefinitivDirectOwnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_78c18456-237d-414c-a36b-529fb8aeaebc" xlink:to="loc_tw_RefinitivDirectOwnerMember_74498aef-bf8c-4b6e-9f99-cd79893fc023" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_892999c3-f67f-4d58-8b48-524e975175b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tw_IncomeTaxDisclosureTable_744908f5-bab9-4596-8014-539d92d77d7c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_892999c3-f67f-4d58-8b48-524e975175b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_892999c3-f67f-4d58-8b48-524e975175b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_892999c3-f67f-4d58-8b48-524e975175b2" xlink:to="loc_us-gaap_ClassOfStockDomain_892999c3-f67f-4d58-8b48-524e975175b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_6e25de69-d807-44ab-94a6-b8b08fd80c69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_892999c3-f67f-4d58-8b48-524e975175b2" xlink:to="loc_us-gaap_ClassOfStockDomain_6e25de69-d807-44ab-94a6-b8b08fd80c69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_5d2b8867-1bbc-44ed-8184-a17b576dec65" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_6e25de69-d807-44ab-94a6-b8b08fd80c69" xlink:to="loc_us-gaap_CommonClassBMember_5d2b8867-1bbc-44ed-8184-a17b576dec65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6b5b543f-f220-44ec-8b3c-814d9cef6f74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tw_IncomeTaxDisclosureTable_744908f5-bab9-4596-8014-539d92d77d7c" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6b5b543f-f220-44ec-8b3c-814d9cef6f74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_6b5b543f-f220-44ec-8b3c-814d9cef6f74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6b5b543f-f220-44ec-8b3c-814d9cef6f74" xlink:to="loc_us-gaap_RelatedPartyDomain_6b5b543f-f220-44ec-8b3c-814d9cef6f74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_8449755e-8ba5-452c-a03d-1be83acb3f4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6b5b543f-f220-44ec-8b3c-814d9cef6f74" xlink:to="loc_us-gaap_RelatedPartyDomain_8449755e-8ba5-452c-a03d-1be83acb3f4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_3e748d2e-9a9f-4f02-a87d-068149b44ed2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_8449755e-8ba5-452c-a03d-1be83acb3f4f" xlink:to="loc_srt_AffiliatedEntityMember_3e748d2e-9a9f-4f02-a87d-068149b44ed2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_bfd873b0-6cf1-4401-be3c-b8bd6f27fa36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_bfd873b0-6cf1-4401-be3c-b8bd6f27fa36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TaxReceivableAgreementRemainingPercentageOfAmountOfFederalStateAndLocalIncomeOrFranchiseTaxSavings_8f5b9021-c969-4a93-8a2f-708aa15844ea" xlink:href="tw-20240630.xsd#tw_TaxReceivableAgreementRemainingPercentageOfAmountOfFederalStateAndLocalIncomeOrFranchiseTaxSavings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_tw_TaxReceivableAgreementRemainingPercentageOfAmountOfFederalStateAndLocalIncomeOrFranchiseTaxSavings_8f5b9021-c969-4a93-8a2f-708aa15844ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_StockContributedDuringPeriodAcquireeMajorityOwner_89abf745-ab6c-405d-a2f1-57ba4a709614" xlink:href="tw-20240630.xsd#tw_StockContributedDuringPeriodAcquireeMajorityOwner"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_tw_StockContributedDuringPeriodAcquireeMajorityOwner_89abf745-ab6c-405d-a2f1-57ba4a709614" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_0a77c619-7ee4-4c22-ba18-0baadbc6dd41" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_us-gaap_CommonStockSharesIssued_0a77c619-7ee4-4c22-ba18-0baadbc6dd41" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxes_269ed355-c201-481d-ba0b-efb5d7ba88bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_IncomeTaxDisclosureLineItems_c85138d2-4472-4b50-9d58-adcdb7eb2d81" xlink:to="loc_us-gaap_AccruedIncomeTaxes_269ed355-c201-481d-ba0b-efb5d7ba88bd" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/NonControllingInterestsScheduleoftheOwnershipInterestinNoncontrollingInterestDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#NonControllingInterestsScheduleoftheOwnershipInterestinNoncontrollingInterestDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/NonControllingInterestsScheduleoftheOwnershipInterestinNoncontrollingInterestDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestTable_1999ed2e-4a27-4be7-ab25-3d00dfa2861f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_us-gaap_MinorityInterestTable_1999ed2e-4a27-4be7-ab25-3d00dfa2861f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_1999ed2e-4a27-4be7-ab25-3d00dfa2861f" xlink:to="loc_srt_OwnershipAxis_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5" xlink:to="loc_srt_OwnershipDomain_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_01d9bcd4-e98a-4987-a78c-862d39febcbc" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_2fdc352c-2ad6-48dc-a6d8-f8b17317f5c5" xlink:to="loc_srt_OwnershipDomain_01d9bcd4-e98a-4987-a78c-862d39febcbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebMarketsLLCMember_6db9bf93-ed70-41c2-9f25-3e647d944307" xlink:href="tw-20240630.xsd#tw_TradewebMarketsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_01d9bcd4-e98a-4987-a78c-862d39febcbc" xlink:to="loc_tw_TradewebMarketsLLCMember_6db9bf93-ed70-41c2-9f25-3e647d944307" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MinorityInterestNumberOfInterestsHeldByParent_221a3ca6-acd6-4c3b-b1f5-79fbc4f76061" xlink:href="tw-20240630.xsd#tw_MinorityInterestNumberOfInterestsHeldByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_tw_MinorityInterestNumberOfInterestsHeldByParent_221a3ca6-acd6-4c3b-b1f5-79fbc4f76061" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MinorityInterestNumberOfInterestsHeldByNoncontrollingOwners_d59bbaac-010c-4197-beee-71ebcd5b48bd" xlink:href="tw-20240630.xsd#tw_MinorityInterestNumberOfInterestsHeldByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_tw_MinorityInterestNumberOfInterestsHeldByNoncontrollingOwners_d59bbaac-010c-4197-beee-71ebcd5b48bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MinorityInterestTotalNumberOfInterests_3ddd27b0-ecf0-4d49-95a5-e4251109b11d" xlink:href="tw-20240630.xsd#tw_MinorityInterestTotalNumberOfInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_tw_MinorityInterestTotalNumberOfInterests_3ddd27b0-ecf0-4d49-95a5-e4251109b11d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_1c050253-ad04-42ad-8fc2-abdab8320105" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_1c050253-ad04-42ad-8fc2-abdab8320105" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_370a18f2-f2d4-48ac-b59a-84940c52ccde" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_370a18f2-f2d4-48ac-b59a-84940c52ccde" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MinorityInterestTotalOwnershipPercentage_7f0c8071-8a20-4724-9e8e-a0f80c20d123" xlink:href="tw-20240630.xsd#tw_MinorityInterestTotalOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_bc371965-c182-4326-9417-3d288574e65e" xlink:to="loc_tw_MinorityInterestTotalOwnershipPercentage_7f0c8071-8a20-4724-9e8e-a0f80c20d123" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/NonControllingInterestsNarrativeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#NonControllingInterestsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/NonControllingInterestsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestLineItems_3cbd9f8e-42d7-4fc8-a410-3ae2282fd7cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestTable_cac93d27-f48e-4199-b7a7-74fbb0029136" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MinorityInterestLineItems_3cbd9f8e-42d7-4fc8-a410-3ae2282fd7cd" xlink:to="loc_us-gaap_MinorityInterestTable_cac93d27-f48e-4199-b7a7-74fbb0029136" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_04a9cc50-db60-4c53-b0bd-7b8274d34e72" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_cac93d27-f48e-4199-b7a7-74fbb0029136" xlink:to="loc_us-gaap_StatementClassOfStockAxis_04a9cc50-db60-4c53-b0bd-7b8274d34e72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_04a9cc50-db60-4c53-b0bd-7b8274d34e72_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04a9cc50-db60-4c53-b0bd-7b8274d34e72" xlink:to="loc_us-gaap_ClassOfStockDomain_04a9cc50-db60-4c53-b0bd-7b8274d34e72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_05f68755-24fb-4ebe-b7fd-b034ecd080ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04a9cc50-db60-4c53-b0bd-7b8274d34e72" xlink:to="loc_us-gaap_ClassOfStockDomain_05f68755-24fb-4ebe-b7fd-b034ecd080ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_06a1d335-3618-4ef4-97df-a40678fb229e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_05f68755-24fb-4ebe-b7fd-b034ecd080ee" xlink:to="loc_us-gaap_CommonClassAMember_06a1d335-3618-4ef4-97df-a40678fb229e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_a559b03d-f207-484a-b8b7-d892af258119" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_05f68755-24fb-4ebe-b7fd-b034ecd080ee" xlink:to="loc_us-gaap_CommonClassBMember_a559b03d-f207-484a-b8b7-d892af258119" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_NoncontrollingInterestConversionRatio_11751ed3-85e1-4b55-96be-c32fa302d977" xlink:href="tw-20240630.xsd#tw_NoncontrollingInterestConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_3cbd9f8e-42d7-4fc8-a410-3ae2282fd7cd" xlink:to="loc_tw_NoncontrollingInterestConversionRatio_11751ed3-85e1-4b55-96be-c32fa302d977" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansScheduleofOutstandingSharesofCommonStockDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#StockholdersEquityandStockBasedCompensationPlansScheduleofOutstandingSharesofCommonStockDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansScheduleofOutstandingSharesofCommonStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_03046c7a-7374-495d-8a2d-41b11cbb3a23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f765cd48-01b6-40f8-92c3-154c466b0cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_03046c7a-7374-495d-8a2d-41b11cbb3a23" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f765cd48-01b6-40f8-92c3-154c466b0cbd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f765cd48-01b6-40f8-92c3-154c466b0cbd" xlink:to="loc_us-gaap_StatementClassOfStockAxis_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da" xlink:to="loc_us-gaap_ClassOfStockDomain_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3c471e0e-4a91-4b81-a3dd-0867b9ccf3da" xlink:to="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_21bceab7-9880-46d4-a4e9-fc1d16a9c420" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:to="loc_us-gaap_CommonClassAMember_21bceab7-9880-46d4-a4e9-fc1d16a9c420" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_b314a5d4-59aa-4df3-8b32-8f17a15dd850" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:to="loc_us-gaap_CommonClassBMember_b314a5d4-59aa-4df3-8b32-8f17a15dd850" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_9ee8d3f1-52c2-4f79-bb8c-a877b82f8701" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:to="loc_us-gaap_CommonClassCMember_9ee8d3f1-52c2-4f79-bb8c-a877b82f8701" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonClassDMember_60769644-8359-4a98-844c-058bb51a2d70" xlink:href="tw-20240630.xsd#tw_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e7cfd2dc-4c1d-42bf-9e87-93de81127761" xlink:to="loc_tw_CommonClassDMember_60769644-8359-4a98-844c-058bb51a2d70" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_d49c3424-edb6-44e4-8c6d-52b69f2cfd23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f765cd48-01b6-40f8-92c3-154c466b0cbd" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_d49c3424-edb6-44e4-8c6d-52b69f2cfd23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d49c3424-edb6-44e4-8c6d-52b69f2cfd23_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d49c3424-edb6-44e4-8c6d-52b69f2cfd23" xlink:to="loc_us-gaap_EquityComponentDomain_d49c3424-edb6-44e4-8c6d-52b69f2cfd23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bfaf04b7-52a9-44db-8ace-f421a7ed6609" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d49c3424-edb6-44e4-8c6d-52b69f2cfd23" xlink:to="loc_us-gaap_EquityComponentDomain_bfaf04b7-52a9-44db-8ace-f421a7ed6609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_820cba62-39f1-4969-9f8b-261f8b6b9d92" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bfaf04b7-52a9-44db-8ace-f421a7ed6609" xlink:to="loc_us-gaap_CommonStockMember_820cba62-39f1-4969-9f8b-261f8b6b9d92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f765cd48-01b6-40f8-92c3-154c466b0cbd" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_54519d73-26fb-472b-be59-a0f5e2839e23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f8c0c463-140a-4bd5-9e5e-a60bb851cdbe" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_54519d73-26fb-472b-be59-a0f5e2839e23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_R8FinMember_80d46de4-ea6e-4d70-83ce-4bb755bdef4a" xlink:href="tw-20240630.xsd#tw_R8FinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_54519d73-26fb-472b-be59-a0f5e2839e23" xlink:to="loc_tw_R8FinMember_80d46de4-ea6e-4d70-83ce-4bb755bdef4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_03046c7a-7374-495d-8a2d-41b11cbb3a23" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_a30da525-4821-43d2-9e8f-f6e170122a75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_a30da525-4821-43d2-9e8f-f6e170122a75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1caab2d0-4f49-49d4-a8e2-a3a4e73bed57" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1caab2d0-4f49-49d4-a8e2-a3a4e73bed57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_be210275-f570-433c-9212-9c4f6d739ca9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_be210275-f570-433c-9212-9c4f6d739ca9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_cd2f9f65-a78d-4ab9-aba8-6d8f0bd474be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_cd2f9f65-a78d-4ab9-aba8-6d8f0bd474be" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_f064fdb0-e5b5-4a17-9de7-bb3aee33c73b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d226dfd7-94af-4c8f-b8af-9572c13ef7eb" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_f064fdb0-e5b5-4a17-9de7-bb3aee33c73b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_0b92ca4f-2e29-4bf5-90e3-36c6bdcab8c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_d83442a9-0dd6-4ed6-9bf4-58f336e9a9a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansNarrativeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#StockholdersEquityandStockBasedCompensationPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:to="loc_us-gaap_AwardTypeAxis_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a2afad58-54bd-4a5b-bcfd-b1b31ae6a283" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_Omnibus2019EquityIncentivePlanMember_eae08a71-def5-42ac-b4b9-dc8bba3efd02" xlink:href="tw-20240630.xsd#tw_Omnibus2019EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:to="loc_tw_Omnibus2019EquityIncentivePlanMember_eae08a71-def5-42ac-b4b9-dc8bba3efd02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_e4c79072-3184-4084-ae3d-64dbd741a65a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_e4c79072-3184-4084-ae3d-64dbd741a65a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_b9ee980a-e688-4006-8667-c317331b888d" xlink:href="tw-20240630.xsd#tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:to="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_b9ee980a-e688-4006-8667-c317331b888d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_8da6c01e-a287-4790-856f-d910d2bad591" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80240bf6-79d9-4c76-9199-b57dea8a9e19" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_8da6c01e-a287-4790-856f-d910d2bad591" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_56f8482e-2f61-4e16-aca4-9c094c6d5ba0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:to="loc_srt_TitleOfIndividualAxis_56f8482e-2f61-4e16-aca4-9c094c6d5ba0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_56f8482e-2f61-4e16-aca4-9c094c6d5ba0_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_56f8482e-2f61-4e16-aca4-9c094c6d5ba0" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_56f8482e-2f61-4e16-aca4-9c094c6d5ba0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4129ac0-a8d4-4abb-9eb7-4277b5bce30d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_56f8482e-2f61-4e16-aca4-9c094c6d5ba0" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4129ac0-a8d4-4abb-9eb7-4277b5bce30d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PresidentMember_ee900a8b-cbc0-4942-8a4c-10997cd38f6c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PresidentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4129ac0-a8d4-4abb-9eb7-4277b5bce30d" xlink:to="loc_srt_PresidentMember_ee900a8b-cbc0-4942-8a4c-10997cd38f6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_f91d98b6-6bc4-4295-899f-01593ab58216" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4129ac0-a8d4-4abb-9eb7-4277b5bce30d" xlink:to="loc_srt_DirectorMember_f91d98b6-6bc4-4295-899f-01593ab58216" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_d72984b5-d839-41d2-b26b-37071f151866" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:to="loc_us-gaap_AwardDateAxis_d72984b5-d839-41d2-b26b-37071f151866" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_d72984b5-d839-41d2-b26b-37071f151866_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_d72984b5-d839-41d2-b26b-37071f151866" xlink:to="loc_us-gaap_AwardDateDomain_d72984b5-d839-41d2-b26b-37071f151866_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_f1129f74-1790-40f9-afae-8b0a7034a883" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_d72984b5-d839-41d2-b26b-37071f151866" xlink:to="loc_us-gaap_AwardDateDomain_f1129f74-1790-40f9-afae-8b0a7034a883" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AwardedDuring2024And2023Member_270c3374-c443-4e46-83d7-a021936d70cc" xlink:href="tw-20240630.xsd#tw_AwardedDuring2024And2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f1129f74-1790-40f9-afae-8b0a7034a883" xlink:to="loc_tw_AwardedDuring2024And2023Member_270c3374-c443-4e46-83d7-a021936d70cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AwardedDuring2022AndPriorMember_c17fde00-c911-4bb5-8d4d-4b41bf245590" xlink:href="tw-20240630.xsd#tw_AwardedDuring2022AndPriorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f1129f74-1790-40f9-afae-8b0a7034a883" xlink:to="loc_tw_AwardedDuring2022AndPriorMember_c17fde00-c911-4bb5-8d4d-4b41bf245590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_632cb9a5-2380-4256-acdb-41ea8beac166" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:to="loc_us-gaap_StatementClassOfStockAxis_632cb9a5-2380-4256-acdb-41ea8beac166" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_632cb9a5-2380-4256-acdb-41ea8beac166_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_632cb9a5-2380-4256-acdb-41ea8beac166" xlink:to="loc_us-gaap_ClassOfStockDomain_632cb9a5-2380-4256-acdb-41ea8beac166_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_689975a3-7bdc-44fc-a143-79e3161322d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_632cb9a5-2380-4256-acdb-41ea8beac166" xlink:to="loc_us-gaap_ClassOfStockDomain_689975a3-7bdc-44fc-a143-79e3161322d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_d5a87d48-2ec6-4696-bc1b-76f5245637a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_689975a3-7bdc-44fc-a143-79e3161322d1" xlink:to="loc_us-gaap_CommonClassAMember_d5a87d48-2ec6-4696-bc1b-76f5245637a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_595d6205-6dc8-4102-b9bc-7777fc33c0a0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_689975a3-7bdc-44fc-a143-79e3161322d1" xlink:to="loc_us-gaap_CommonClassBMember_595d6205-6dc8-4102-b9bc-7777fc33c0a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_83e857d5-2dc6-4fbe-aae9-4322d5782fe4" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_278c9bc9-6a31-4d06-85f4-f8c2536a13ab" xlink:to="loc_srt_StatementScenarioAxis_83e857d5-2dc6-4fbe-aae9-4322d5782fe4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_83e857d5-2dc6-4fbe-aae9-4322d5782fe4_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_83e857d5-2dc6-4fbe-aae9-4322d5782fe4" xlink:to="loc_srt_ScenarioUnspecifiedDomain_83e857d5-2dc6-4fbe-aae9-4322d5782fe4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_b08e5e7a-57b3-4c13-ba27-47ea1f9e4dd7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_83e857d5-2dc6-4fbe-aae9-4322d5782fe4" xlink:to="loc_srt_ScenarioUnspecifiedDomain_b08e5e7a-57b3-4c13-ba27-47ea1f9e4dd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_084fcb27-1c5a-4b8d-8371-0d80720ba63a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_b08e5e7a-57b3-4c13-ba27-47ea1f9e4dd7" xlink:to="loc_srt_ScenarioForecastMember_084fcb27-1c5a-4b8d-8371-0d80720ba63a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7c80c69a-1b84-47d2-a7bd-5652482db1f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7c80c69a-1b84-47d2-a7bd-5652482db1f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fcd49b29-8d9e-4566-a90d-6507019ff7bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fcd49b29-8d9e-4566-a90d-6507019ff7bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_bc697bd2-82eb-4090-b053-54a92f13ea1b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_bc697bd2-82eb-4090-b053-54a92f13ea1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_ed1931c2-0f30-4f54-bdff-22113a20dca9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_ed1931c2-0f30-4f54-bdff-22113a20dca9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_7ee1fe0d-88f0-4024-a312-6f3edd5e72f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_7ee1fe0d-88f0-4024-a312-6f3edd5e72f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ab1a0588-6977-4d38-92e2-64f9410251b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ab1a0588-6977-4d38-92e2-64f9410251b2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_33babeaa-6db8-44db-811c-b8839ed025cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_33babeaa-6db8-44db-811c-b8839ed025cf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6686b742-9c54-40ba-95d9-060b04305fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6686b742-9c54-40ba-95d9-060b04305fb5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_e15b1cb4-0b8a-4da1-a414-ad26b8d9590a" xlink:href="tw-20240630.xsd#tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_e15b1cb4-0b8a-4da1-a414-ad26b8d9590a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumPerformanceModifier_9fa56ec7-e9a2-420e-bc95-f02c46e35e9d" xlink:href="tw-20240630.xsd#tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumPerformanceModifier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumPerformanceModifier_9fa56ec7-e9a2-420e-bc95-f02c46e35e9d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumPerformanceModifier_a741f0d6-09b7-4595-836a-9db101378449" xlink:href="tw-20240630.xsd#tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumPerformanceModifier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumPerformanceModifier_a741f0d6-09b7-4595-836a-9db101378449" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPerformanceModifier_736604b2-7536-440e-ace1-77a12034e6cd" xlink:href="tw-20240630.xsd#tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPerformanceModifier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_tw_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPerformanceModifier_736604b2-7536-440e-ace1-77a12034e6cd" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_ad6bdc9f-5f70-4eb9-8199-cd7009b27b2e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_ad6bdc9f-5f70-4eb9-8199-cd7009b27b2e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_752bff7a-8690-46fa-a433-fb2c9de0815d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_752bff7a-8690-46fa-a433-fb2c9de0815d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_c04dd0aa-4cae-466f-88a0-edb0b28c03a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_c04dd0aa-4cae-466f-88a0-edb0b28c03a1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_88f57eb3-f3c7-487d-8f82-367de79f8c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_88f57eb3-f3c7-487d-8f82-367de79f8c4e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_b1562b92-6bf6-4d83-a7a5-bc874cfc084d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_b1562b92-6bf6-4d83-a7a5-bc874cfc084d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_CommonStockConversionRatio_2cc96931-9e61-4d65-b33f-9637d4ccd843" xlink:href="tw-20240630.xsd#tw_CommonStockConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_tw_CommonStockConversionRatio_2cc96931-9e61-4d65-b33f-9637d4ccd843" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_77075a41-deb2-48c3-9606-0c414936979e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_77075a41-deb2-48c3-9606-0c414936979e" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_27a44858-a95b-452a-887e-5a4d19b46cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_27a44858-a95b-452a-887e-5a4d19b46cc7" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_a9903bd4-40de-4841-bc0f-e447b0af8872" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_63e8f1eb-b17b-4451-8164-a07acadbd46a" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_a9903bd4-40de-4841-bc0f-e447b0af8872" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansScheduleofSignificantValuationAssumptionsUsedToEstimateTheGrantDateFairValueofPSUsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#StockholdersEquityandStockBasedCompensationPlansScheduleofSignificantValuationAssumptionsUsedToEstimateTheGrantDateFairValueofPSUsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/StockholdersEquityandStockBasedCompensationPlansScheduleofSignificantValuationAssumptionsUsedToEstimateTheGrantDateFairValueofPSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9e056946-597d-43ba-9ba5-320643c475b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cea225fa-6ef2-4e39-ae61-0b387172ecb3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9e056946-597d-43ba-9ba5-320643c475b0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cea225fa-6ef2-4e39-ae61-0b387172ecb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_83c0b864-585f-4789-a25d-1e23d912c012" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cea225fa-6ef2-4e39-ae61-0b387172ecb3" xlink:to="loc_us-gaap_AwardTypeAxis_83c0b864-585f-4789-a25d-1e23d912c012" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83c0b864-585f-4789-a25d-1e23d912c012_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_83c0b864-585f-4789-a25d-1e23d912c012" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83c0b864-585f-4789-a25d-1e23d912c012_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7a4f7da8-0419-44ee-a39a-bddb575fcef1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_83c0b864-585f-4789-a25d-1e23d912c012" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7a4f7da8-0419-44ee-a39a-bddb575fcef1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_83f22b7d-4136-456e-a006-98079fa4b89f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7a4f7da8-0419-44ee-a39a-bddb575fcef1" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_83f22b7d-4136-456e-a006-98079fa4b89f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_03530011-3292-40e0-88a0-388007dfc0ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9e056946-597d-43ba-9ba5-320643c475b0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_03530011-3292-40e0-88a0-388007dfc0ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_bd23a379-d843-4999-9a32-7e908022752b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9e056946-597d-43ba-9ba5-320643c475b0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_bd23a379-d843-4999-9a32-7e908022752b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_80d5603e-774c-47d7-a6bc-15ef15f33bde" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9e056946-597d-43ba-9ba5-320643c475b0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_80d5603e-774c-47d7-a6bc-15ef15f33bde" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/RelatedPartyTransactionsBalancesScheduleofBalancesFromTransactionswithAffiliatesIncludedintheConsolidatedStatementsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#RelatedPartyTransactionsBalancesScheduleofBalancesFromTransactionswithAffiliatesIncludedintheConsolidatedStatementsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/RelatedPartyTransactionsBalancesScheduleofBalancesFromTransactionswithAffiliatesIncludedintheConsolidatedStatementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_721cc889-203a-478d-9272-87a14f661bfe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_721cc889-203a-478d-9272-87a14f661bfe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_44baa95f-c3cf-48b3-9c0f-8363a5e1a218" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_721cc889-203a-478d-9272-87a14f661bfe" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_44baa95f-c3cf-48b3-9c0f-8363a5e1a218" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_44baa95f-c3cf-48b3-9c0f-8363a5e1a218_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_44baa95f-c3cf-48b3-9c0f-8363a5e1a218" xlink:to="loc_us-gaap_RelatedPartyDomain_44baa95f-c3cf-48b3-9c0f-8363a5e1a218_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_9c8eac09-ceaf-41ea-9ee2-e1bdc205b1e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_44baa95f-c3cf-48b3-9c0f-8363a5e1a218" xlink:to="loc_us-gaap_RelatedPartyDomain_9c8eac09-ceaf-41ea-9ee2-e1bdc205b1e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_f50e4ec0-46d8-4e65-aace-7e6bda127bd6" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_9c8eac09-ceaf-41ea-9ee2-e1bdc205b1e1" xlink:to="loc_srt_AffiliatedEntityMember_f50e4ec0-46d8-4e65-aace-7e6bda127bd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_7678eec0-f317-4b89-8cfe-78e3f5157f7e" xlink:href="tw-20240630.xsd#tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_7678eec0-f317-4b89-8cfe-78e3f5157f7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivables_1ab15419-83dc-49cd-a39b-43d58ef73e57" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_OtherReceivables_1ab15419-83dc-49cd-a39b-43d58ef73e57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_73dec0b6-3321-4844-99cf-1fad65727d56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_OtherAssets_73dec0b6-3321-4844-99cf-1fad65727d56" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_60ffa847-6ceb-4e1b-86d5-b36353c2e5d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_60ffa847-6ceb-4e1b-86d5-b36353c2e5d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_1af546a7-30cd-4523-85da-eab53c7bc483" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_ContractWithCustomerLiability_1af546a7-30cd-4523-85da-eab53c7bc483" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_f978bab7-4808-4828-8c53-1756b8c03975" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_14601a71-1515-4858-8a93-1860569f5e4f" xlink:to="loc_us-gaap_OtherLiabilities_f978bab7-4808-4828-8c53-1756b8c03975" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/RelatedPartyTransactionsScheduleofAffiliateswereIncludedintheConsolidatedStatementsofIncomeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#RelatedPartyTransactionsScheduleofAffiliateswereIncludedintheConsolidatedStatementsofIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/RelatedPartyTransactionsScheduleofAffiliateswereIncludedintheConsolidatedStatementsofIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_0d657a36-777e-4a34-81fd-7630fde86bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b984299d-babe-487a-b697-a5a155418ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_0d657a36-777e-4a34-81fd-7630fde86bc7" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b984299d-babe-487a-b697-a5a155418ad2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_bc8f88cd-f7fa-403d-843e-d06e5fa49062" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b984299d-babe-487a-b697-a5a155418ad2" xlink:to="loc_srt_ProductOrServiceAxis_bc8f88cd-f7fa-403d-843e-d06e5fa49062" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_bc8f88cd-f7fa-403d-843e-d06e5fa49062_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_bc8f88cd-f7fa-403d-843e-d06e5fa49062" xlink:to="loc_srt_ProductsAndServicesDomain_bc8f88cd-f7fa-403d-843e-d06e5fa49062_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_bbefe02d-755e-4ff7-af4a-66772f77349a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_bc8f88cd-f7fa-403d-843e-d06e5fa49062" xlink:to="loc_srt_ProductsAndServicesDomain_bbefe02d-755e-4ff7-af4a-66772f77349a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_SubscriptionFeeRevenueMember_a9f7a2c1-0e72-4f94-8978-096a25e12b89" xlink:href="tw-20240630.xsd#tw_SubscriptionFeeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_bbefe02d-755e-4ff7-af4a-66772f77349a" xlink:to="loc_tw_SubscriptionFeeRevenueMember_a9f7a2c1-0e72-4f94-8978-096a25e12b89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MarketDataRevenueMember_0b522744-d0a5-4666-8ed3-5da84851f6f0" xlink:href="tw-20240630.xsd#tw_MarketDataRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_bbefe02d-755e-4ff7-af4a-66772f77349a" xlink:to="loc_tw_MarketDataRevenueMember_0b522744-d0a5-4666-8ed3-5da84851f6f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialServiceOtherMember_61fad12d-c78f-4fa3-8eb1-1a5ed6659db6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_bbefe02d-755e-4ff7-af4a-66772f77349a" xlink:to="loc_us-gaap_FinancialServiceOtherMember_61fad12d-c78f-4fa3-8eb1-1a5ed6659db6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1f633663-cb60-491c-863c-a593938e4a1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_b984299d-babe-487a-b697-a5a155418ad2" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1f633663-cb60-491c-863c-a593938e4a1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_1f633663-cb60-491c-863c-a593938e4a1f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1f633663-cb60-491c-863c-a593938e4a1f" xlink:to="loc_us-gaap_RelatedPartyDomain_1f633663-cb60-491c-863c-a593938e4a1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_7f317506-2aa8-4d87-83f7-6b18418fa336" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1f633663-cb60-491c-863c-a593938e4a1f" xlink:to="loc_us-gaap_RelatedPartyDomain_7f317506-2aa8-4d87-83f7-6b18418fa336" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_bcc0e767-ccfe-48f6-b533-b95aa9c1a9af" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_7f317506-2aa8-4d87-83f7-6b18418fa336" xlink:to="loc_srt_AffiliatedEntityMember_bcc0e767-ccfe-48f6-b533-b95aa9c1a9af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_b0a7a029-efff-4ce6-a5f0-5910437e5bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_0d657a36-777e-4a34-81fd-7630fde86bc7" xlink:to="loc_us-gaap_RevenuesAbstract_b0a7a029-efff-4ce6-a5f0-5910437e5bd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_ae09f653-2e86-4c83-9194-5abff2488c6d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_b0a7a029-efff-4ce6-a5f0-5910437e5bd8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_ae09f653-2e86-4c83-9194-5abff2488c6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_0d657a36-777e-4a34-81fd-7630fde86bc7" xlink:to="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_ca8337b1-f755-4ff2-82cb-edd391c9f503" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:to="loc_us-gaap_LaborAndRelatedExpense_ca8337b1-f755-4ff2-82cb-edd391c9f503" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommunicationsAndInformationTechnology_2b5350fc-8045-4704-8d2f-ad7e44f99175" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommunicationsAndInformationTechnology"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:to="loc_us-gaap_CommunicationsAndInformationTechnology_2b5350fc-8045-4704-8d2f-ad7e44f99175" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_OtherGeneralAndAdministrativeExpenseNetOfReclassification_8af9b02c-70c6-466a-b8bf-31e066b6f195" xlink:href="tw-20240630.xsd#tw_OtherGeneralAndAdministrativeExpenseNetOfReclassification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:to="loc_tw_OtherGeneralAndAdministrativeExpenseNetOfReclassification_8af9b02c-70c6-466a-b8bf-31e066b6f195" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_1c85eeb4-0124-4591-b388-eae1fde799ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfessionalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:to="loc_us-gaap_ProfessionalFees_1c85eeb4-0124-4591-b388-eae1fde799ad" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_16b483f2-acc8-4b65-8563-ff2d6c8164bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OccupancyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestIncomeSecuritiesOperatingByTaxableStatusAbstract_e57fdda6-d99c-4f67-8096-e42d96c5ca37" xlink:to="loc_us-gaap_OccupancyNet_16b483f2-acc8-4b65-8563-ff2d6c8164bd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsMeasuredatFairValueDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsMeasuredatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsMeasuredatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_ad582705-0f2c-4ebd-9090-a09767236488" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_ad582705-0f2c-4ebd-9090-a09767236488" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9a585204-a32d-4fc5-9b0a-b9b00af7d695" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_ad582705-0f2c-4ebd-9090-a09767236488" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9a585204-a32d-4fc5-9b0a-b9b00af7d695" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9a585204-a32d-4fc5-9b0a-b9b00af7d695_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9a585204-a32d-4fc5-9b0a-b9b00af7d695" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9a585204-a32d-4fc5-9b0a-b9b00af7d695_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6441849b-443a-4d41-bbd3-47d6932f77be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9a585204-a32d-4fc5-9b0a-b9b00af7d695" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6441849b-443a-4d41-bbd3-47d6932f77be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_40f0eb6f-6f05-4f2c-a7d4-eb43f4cba5f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6441849b-443a-4d41-bbd3-47d6932f77be" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_40f0eb6f-6f05-4f2c-a7d4-eb43f4cba5f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_0b94a5ef-455a-4914-a01d-1835470230c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6441849b-443a-4d41-bbd3-47d6932f77be" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_0b94a5ef-455a-4914-a01d-1835470230c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_79c6a39a-6e83-44d8-a0a6-89bbe5ac2069" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6441849b-443a-4d41-bbd3-47d6932f77be" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_79c6a39a-6e83-44d8-a0a6-89bbe5ac2069" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_ff1f83f9-f66e-4640-b394-e09a8a327665" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_ad582705-0f2c-4ebd-9090-a09767236488" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_ff1f83f9-f66e-4640-b394-e09a8a327665" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_ff1f83f9-f66e-4640-b394-e09a8a327665_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ff1f83f9-f66e-4640-b394-e09a8a327665" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_ff1f83f9-f66e-4640-b394-e09a8a327665_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_f961d66a-cf06-477a-97a0-8aef68bcdf4c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ff1f83f9-f66e-4640-b394-e09a8a327665" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_f961d66a-cf06-477a-97a0-8aef68bcdf4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsMember_33957ec4-3d2c-437d-91ab-d78aa8d4bac9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_f961d66a-cf06-477a-97a0-8aef68bcdf4c" xlink:to="loc_us-gaap_CashEquivalentsMember_33957ec4-3d2c-437d-91ab-d78aa8d4bac9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_OtherReceivablesMember_8e14062a-f5bd-4e0b-9dcb-47b1da81c497" xlink:href="tw-20240630.xsd#tw_OtherReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_f961d66a-cf06-477a-97a0-8aef68bcdf4c" xlink:to="loc_tw_OtherReceivablesMember_8e14062a-f5bd-4e0b-9dcb-47b1da81c497" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_31e55f25-af4b-4e4f-b444-c0783e6bc6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:to="loc_us-gaap_DerivativeAssets_31e55f25-af4b-4e4f-b444-c0783e6bc6e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_3a668d82-d106-4270-a3f7-f5a85ca9d4d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_3a668d82-d106-4270-a3f7-f5a85ca9d4d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_e1ce55fd-20a0-4faa-89c3-d8624fff7f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_e1ce55fd-20a0-4faa-89c3-d8624fff7f7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_78b67680-88ac-4c49-8096-1fdcc70e7c74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_82490888-259d-497e-ac8c-9d1e9b9d5cb2" xlink:to="loc_us-gaap_DerivativeLiabilities_78b67680-88ac-4c49-8096-1fdcc70e7c74" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsNarrativeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#FairValueofFinancialInstrumentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c29cba39-633d-4c60-bab4-2c98a36b3463" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c29cba39-633d-4c60-bab4-2c98a36b3463" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_51cc9719-6df0-486b-a7f5-63a2ee6e6713" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c29cba39-633d-4c60-bab4-2c98a36b3463" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_51cc9719-6df0-486b-a7f5-63a2ee6e6713" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_51cc9719-6df0-486b-a7f5-63a2ee6e6713_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_51cc9719-6df0-486b-a7f5-63a2ee6e6713" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_51cc9719-6df0-486b-a7f5-63a2ee6e6713_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_2b5efcc2-1032-449a-b372-20708fec52cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_51cc9719-6df0-486b-a7f5-63a2ee6e6713" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_2b5efcc2-1032-449a-b372-20708fec52cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_223b77f1-6f50-45d4-8bb8-baaff8d47f80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_2b5efcc2-1032-449a-b372-20708fec52cc" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_223b77f1-6f50-45d4-8bb8-baaff8d47f80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_6b4e9497-1595-471c-a4cd-ef1b0258de76" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c29cba39-633d-4c60-bab4-2c98a36b3463" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_6b4e9497-1595-471c-a4cd-ef1b0258de76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_6b4e9497-1595-471c-a4cd-ef1b0258de76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6b4e9497-1595-471c-a4cd-ef1b0258de76" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_6b4e9497-1595-471c-a4cd-ef1b0258de76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_13e9d441-cbd4-4acb-b312-dae113a30e10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6b4e9497-1595-471c-a4cd-ef1b0258de76" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_13e9d441-cbd4-4acb-b312-dae113a30e10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeOptionMember_5b23b898-9ff9-4f65-80cb-554e70dd5835" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_13e9d441-cbd4-4acb-b312-dae113a30e10" xlink:to="loc_us-gaap_ForeignExchangeOptionMember_5b23b898-9ff9-4f65-80cb-554e70dd5835" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_923cea5f-ddd6-47b0-adad-d9bda393123b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c29cba39-633d-4c60-bab4-2c98a36b3463" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_923cea5f-ddd6-47b0-adad-d9bda393123b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_923cea5f-ddd6-47b0-adad-d9bda393123b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_923cea5f-ddd6-47b0-adad-d9bda393123b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_923cea5f-ddd6-47b0-adad-d9bda393123b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b3f0cd82-adc0-4f4c-8ca7-37dfecbcd91c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_923cea5f-ddd6-47b0-adad-d9bda393123b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b3f0cd82-adc0-4f4c-8ca7-37dfecbcd91c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleNotesPayableMember_973cc85e-13bd-4f00-9392-a0ae995e64b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConvertibleNotesPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_b3f0cd82-adc0-4f4c-8ca7-37dfecbcd91c" xlink:to="loc_us-gaap_ConvertibleNotesPayableMember_973cc85e-13bd-4f00-9392-a0ae995e64b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_6bcdb0bf-f342-4a8d-ae0a-160a9fe15aa5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_6bcdb0bf-f342-4a8d-ae0a-160a9fe15aa5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_32d4e579-a58c-48e7-867d-50720f381c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_32d4e579-a58c-48e7-867d-50720f381c7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded_659dfb32-5f54-412a-b14a-80e6596b2144" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded_659dfb32-5f54-412a-b14a-80e6596b2144" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_ef4bab71-1b8b-4987-b35e-c5af54f45677" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_ef4bab71-1b8b-4987-b35e-c5af54f45677" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_cc5d8039-09fa-4683-a3de-41e5bbc2fb3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_DerivativeNotionalAmount_cc5d8039-09fa-4683-a3de-41e5bbc2fb3a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_981cf222-b86e-4320-9f2f-d8a2383379ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f5bd15f0-cb3b-4f9d-a582-6a0ea09337c7" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_981cf222-b86e-4320-9f2f-d8a2383379ad" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofForeignExchangeDerivativeContractsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#FairValueofFinancialInstrumentsScheduleofForeignExchangeDerivativeContractsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofForeignExchangeDerivativeContractsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_1e90c1f7-07b9-4d9c-833b-dbe047d44890" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_1cd6d9b4-b053-4bb9-af6c-abcff20ac514" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_1e90c1f7-07b9-4d9c-833b-dbe047d44890" xlink:to="loc_us-gaap_DerivativeTable_1cd6d9b4-b053-4bb9-af6c-abcff20ac514" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_c8f16d5b-9688-4770-8b51-e31196fa5aa8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_1cd6d9b4-b053-4bb9-af6c-abcff20ac514" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_c8f16d5b-9688-4770-8b51-e31196fa5aa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c8f16d5b-9688-4770-8b51-e31196fa5aa8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c8f16d5b-9688-4770-8b51-e31196fa5aa8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c8f16d5b-9688-4770-8b51-e31196fa5aa8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4fae038b-0806-45d3-b69b-469cdcacf177" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c8f16d5b-9688-4770-8b51-e31196fa5aa8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4fae038b-0806-45d3-b69b-469cdcacf177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_67a3b3ad-f2e1-468b-a56d-2056a8f8679b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4fae038b-0806-45d3-b69b-469cdcacf177" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_67a3b3ad-f2e1-468b-a56d-2056a8f8679b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeOptionMember_07412c87-365a-42b6-b17d-3590dc2afb91" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4fae038b-0806-45d3-b69b-469cdcacf177" xlink:to="loc_us-gaap_ForeignExchangeOptionMember_07412c87-365a-42b6-b17d-3590dc2afb91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_4352150b-954c-4d62-9dfe-8aa6452e6a88" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_1cd6d9b4-b053-4bb9-af6c-abcff20ac514" xlink:to="loc_us-gaap_HedgingDesignationAxis_4352150b-954c-4d62-9dfe-8aa6452e6a88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_4352150b-954c-4d62-9dfe-8aa6452e6a88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_4352150b-954c-4d62-9dfe-8aa6452e6a88" xlink:to="loc_us-gaap_HedgingDesignationDomain_4352150b-954c-4d62-9dfe-8aa6452e6a88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_aaa86729-7e84-4fa8-a354-117d5a03cae1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_4352150b-954c-4d62-9dfe-8aa6452e6a88" xlink:to="loc_us-gaap_HedgingDesignationDomain_aaa86729-7e84-4fa8-a354-117d5a03cae1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_f83f108c-4be0-42e4-b5f8-f20e18adae8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_aaa86729-7e84-4fa8-a354-117d5a03cae1" xlink:to="loc_us-gaap_NondesignatedMember_f83f108c-4be0-42e4-b5f8-f20e18adae8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_38f77a8c-ccd7-4182-b068-ee00713ba6dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_1e90c1f7-07b9-4d9c-833b-dbe047d44890" xlink:to="loc_us-gaap_DerivativeNotionalAmount_38f77a8c-ccd7-4182-b068-ee00713ba6dc" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofUnrealizedGainsLossesonForeignCurrencyForwardsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#FairValueofFinancialInstrumentsScheduleofUnrealizedGainsLossesonForeignCurrencyForwardsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofUnrealizedGainsLossesonForeignCurrencyForwardsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_6f32193a-e66a-4fbb-82a7-7c4910c438eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_7c478917-46de-4b56-8030-ccb31cf5d813" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_6f32193a-e66a-4fbb-82a7-7c4910c438eb" xlink:to="loc_us-gaap_DerivativeTable_7c478917-46de-4b56-8030-ccb31cf5d813" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_b1af8c28-6639-406d-8d8f-1977f9803db5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7c478917-46de-4b56-8030-ccb31cf5d813" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_b1af8c28-6639-406d-8d8f-1977f9803db5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_b1af8c28-6639-406d-8d8f-1977f9803db5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b1af8c28-6639-406d-8d8f-1977f9803db5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_b1af8c28-6639-406d-8d8f-1977f9803db5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_bcf313be-a611-4940-9c30-e4c713c3af22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b1af8c28-6639-406d-8d8f-1977f9803db5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_bcf313be-a611-4940-9c30-e4c713c3af22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_6f6c80d4-bf5c-4c04-b4a2-1994e0590801" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_bcf313be-a611-4940-9c30-e4c713c3af22" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_6f6c80d4-bf5c-4c04-b4a2-1994e0590801" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeOptionMember_f8bd8860-98d5-49c8-bfd0-b72c3b7911d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_bcf313be-a611-4940-9c30-e4c713c3af22" xlink:to="loc_us-gaap_ForeignExchangeOptionMember_f8bd8860-98d5-49c8-bfd0-b72c3b7911d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_38a514a6-4a42-4425-bb2b-b32829adc58b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7c478917-46de-4b56-8030-ccb31cf5d813" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_38a514a6-4a42-4425-bb2b-b32829adc58b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_38a514a6-4a42-4425-bb2b-b32829adc58b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_38a514a6-4a42-4425-bb2b-b32829adc58b" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_38a514a6-4a42-4425-bb2b-b32829adc58b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3cfddfc2-c267-4ef0-80f5-240261f83efa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_38a514a6-4a42-4425-bb2b-b32829adc58b" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3cfddfc2-c267-4ef0-80f5-240261f83efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_4890e7c2-f383-4388-bc23-28931c3f2083" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3cfddfc2-c267-4ef0-80f5-240261f83efa" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_4890e7c2-f383-4388-bc23-28931c3f2083" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseMember_ba9eeccb-6205-402c-a8cc-aeae20ce7f22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherOperatingIncomeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3cfddfc2-c267-4ef0-80f5-240261f83efa" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseMember_ba9eeccb-6205-402c-a8cc-aeae20ce7f22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_4bfc495f-88a4-4716-a990-fc262e926e0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6f32193a-e66a-4fbb-82a7-7c4910c438eb" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_4bfc495f-88a4-4716-a990-fc262e926e0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities_272b9914-766e-4129-845b-cbd8de8c7864" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6f32193a-e66a-4fbb-82a7-7c4910c438eb" xlink:to="loc_us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities_272b9914-766e-4129-845b-cbd8de8c7864" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsNotMeasuredatFairValueDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsNotMeasuredatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/FairValueofFinancialInstrumentsScheduleofFinancialInstrumentsNotMeasuredatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0a0029cf-bd95-4c42-9c7e-8dd68f794500" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7b3ae88a-8e57-4dd6-9297-676a4f8646bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0a0029cf-bd95-4c42-9c7e-8dd68f794500" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7b3ae88a-8e57-4dd6-9297-676a4f8646bd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7b3ae88a-8e57-4dd6-9297-676a4f8646bd" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08c9b9fb-51e7-4d55-8227-7f3488ea38b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_de6ffe74-f596-4cb7-9df9-7b6a282cd3a3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08c9b9fb-51e7-4d55-8227-7f3488ea38b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel12And3Member_2dba68b5-ba00-4670-af84-09c15b94803f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel12And3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08c9b9fb-51e7-4d55-8227-7f3488ea38b7" xlink:to="loc_us-gaap_FairValueInputsLevel12And3Member_2dba68b5-ba00-4670-af84-09c15b94803f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_46ead1ea-4dd9-4e11-9c20-d337d272eba8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_2dba68b5-ba00-4670-af84-09c15b94803f" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_46ead1ea-4dd9-4e11-9c20-d337d272eba8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_513013e1-1947-48ed-8663-e526e8a0999a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_2dba68b5-ba00-4670-af84-09c15b94803f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_513013e1-1947-48ed-8663-e526e8a0999a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_16af5629-7f0b-4f7b-9686-521f3fda51fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_2dba68b5-ba00-4670-af84-09c15b94803f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_16af5629-7f0b-4f7b-9686-521f3fda51fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ecfab112-bcfa-4ca9-b153-d32771126e6d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7b3ae88a-8e57-4dd6-9297-676a4f8646bd" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ecfab112-bcfa-4ca9-b153-d32771126e6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_ecfab112-bcfa-4ca9-b153-d32771126e6d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ecfab112-bcfa-4ca9-b153-d32771126e6d" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_ecfab112-bcfa-4ca9-b153-d32771126e6d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_cdfcf79d-6395-4a08-b77d-e72913bcd272" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ecfab112-bcfa-4ca9-b153-d32771126e6d" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_cdfcf79d-6395-4a08-b77d-e72913bcd272" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_90c80f3e-fac0-4eb1-837d-4f3afbdd192c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_cdfcf79d-6395-4a08-b77d-e72913bcd272" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_90c80f3e-fac0-4eb1-837d-4f3afbdd192c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0a0029cf-bd95-4c42-9c7e-8dd68f794500" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RestrictedCashAndCashEquivalentsFairValueDisclosure_4796b87a-b2a1-4725-86b8-5ce50f71dc36" xlink:href="tw-20240630.xsd#tw_RestrictedCashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_tw_RestrictedCashAndCashEquivalentsFairValueDisclosure_4796b87a-b2a1-4725-86b8-5ce50f71dc36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_fd5cde76-52da-49fc-87cd-2eb39215b2b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_fd5cde76-52da-49fc-87cd-2eb39215b2b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities_646986e2-cc51-4d03-87a2-5f574470fcc6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_us-gaap_DepositsWithClearingOrganizationsAndOthersSecurities_646986e2-cc51-4d03-87a2-5f574470fcc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_4c2935d9-532b-4a5c-9675-877ce38b7865" xlink:href="tw-20240630.xsd#tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_tw_AccountReceivableExcludingReceivableFromBrokersAndDealersAndClearingOrganizationsNetOfAllowance_4c2935d9-532b-4a5c-9675-877ce38b7865" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromClearingOrganizations_9645e876-24fb-4717-9e85-675f81cf85b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_us-gaap_ReceivablesFromClearingOrganizations_9645e876-24fb-4717-9e85-675f81cf85b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_7782aed7-d2d1-46d4-94cf-5f25b4320302" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_02874825-2201-41fb-8be1-10d168fff4db" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_7782aed7-d2d1-46d4-94cf-5f25b4320302" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_b816eb20-5670-4965-85a3-589f721f79fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0a0029cf-bd95-4c42-9c7e-8dd68f794500" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_b816eb20-5670-4965-85a3-589f721f79fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_17a663a2-f9a0-4830-bcce-0a0e578e7de3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_b816eb20-5670-4965-85a3-589f721f79fa" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_17a663a2-f9a0-4830-bcce-0a0e578e7de3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_68cae030-94dc-4238-8dbe-c04c1bcc2411" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_b816eb20-5670-4965-85a3-589f721f79fa" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_68cae030-94dc-4238-8dbe-c04c1bcc2411" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_65a17c07-9039-4cd6-aadd-c23fdd454a82" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_b816eb20-5670-4965-85a3-589f721f79fa" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_65a17c07-9039-4cd6-aadd-c23fdd454a82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_454b44ac-9620-4ce5-9bf4-f29e444b5366" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_3fa73f75-5726-4d28-a86c-9f75242a5d42" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_3fa73f75-5726-4d28-a86c-9f75242a5d42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3fa73f75-5726-4d28-a86c-9f75242a5d42_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3fa73f75-5726-4d28-a86c-9f75242a5d42" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3fa73f75-5726-4d28-a86c-9f75242a5d42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d074beef-0d29-447d-8141-94e82cef9665" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3fa73f75-5726-4d28-a86c-9f75242a5d42" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d074beef-0d29-447d-8141-94e82cef9665" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_b16d15d6-2c38-4972-98c0-6c793a13cac2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d074beef-0d29-447d-8141-94e82cef9665" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_b16d15d6-2c38-4972-98c0-6c793a13cac2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_41bcdc8b-73a1-486a-b78a-ccd496fae992" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:to="loc_us-gaap_CreditFacilityAxis_41bcdc8b-73a1-486a-b78a-ccd496fae992" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_41bcdc8b-73a1-486a-b78a-ccd496fae992_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_41bcdc8b-73a1-486a-b78a-ccd496fae992" xlink:to="loc_us-gaap_CreditFacilityDomain_41bcdc8b-73a1-486a-b78a-ccd496fae992_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6b5189da-a03c-4678-bbd2-d78d8de7e4cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_41bcdc8b-73a1-486a-b78a-ccd496fae992" xlink:to="loc_us-gaap_CreditFacilityDomain_6b5189da-a03c-4678-bbd2-d78d8de7e4cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_45df2b53-4e63-461f-ae0b-3c1172b71919" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6b5189da-a03c-4678-bbd2-d78d8de7e4cc" xlink:to="loc_us-gaap_LetterOfCreditMember_45df2b53-4e63-461f-ae0b-3c1172b71919" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BridgeLoanMember_4808dc14-bf69-4fdd-adb4-2d2dea87b14e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BridgeLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6b5189da-a03c-4678-bbd2-d78d8de7e4cc" xlink:to="loc_us-gaap_BridgeLoanMember_4808dc14-bf69-4fdd-adb4-2d2dea87b14e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_cdfdc99c-69a7-490e-a036-8506fc684b51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:to="loc_us-gaap_VariableRateAxis_cdfdc99c-69a7-490e-a036-8506fc684b51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_cdfdc99c-69a7-490e-a036-8506fc684b51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_cdfdc99c-69a7-490e-a036-8506fc684b51" xlink:to="loc_us-gaap_VariableRateDomain_cdfdc99c-69a7-490e-a036-8506fc684b51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_cdfdc99c-69a7-490e-a036-8506fc684b51" xlink:to="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_d6db07cb-0fbf-431f-a3bd-e41f96e62967" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalFundsEffectiveSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_d6db07cb-0fbf-431f-a3bd-e41f96e62967" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_OneMonthSecuredOvernightFinancingRateMember_ea242e7e-5915-4e22-b57e-ebf16192f776" xlink:href="tw-20240630.xsd#tw_OneMonthSecuredOvernightFinancingRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:to="loc_tw_OneMonthSecuredOvernightFinancingRateMember_ea242e7e-5915-4e22-b57e-ebf16192f776" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_f1fffde7-4cae-42f4-b014-41950f6b4558" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_f1fffde7-4cae-42f4-b014-41950f6b4558" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_EURIBORMember_81209ed9-eb4a-495f-a7f1-35ae5b28e195" xlink:href="tw-20240630.xsd#tw_EURIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_89c7be82-0004-452c-b7f0-56f6d5026ee1" xlink:to="loc_tw_EURIBORMember_81209ed9-eb4a-495f-a7f1-35ae5b28e195" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_472ba386-1fe0-4a9e-974d-afcf0829e2ab" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dcaa78c4-ffc3-42fe-8736-90339c67465f" xlink:to="loc_srt_RangeAxis_472ba386-1fe0-4a9e-974d-afcf0829e2ab" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_472ba386-1fe0-4a9e-974d-afcf0829e2ab_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_472ba386-1fe0-4a9e-974d-afcf0829e2ab" xlink:to="loc_srt_RangeMember_472ba386-1fe0-4a9e-974d-afcf0829e2ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_320eebdf-04a3-4561-b0e2-9a2af2a61bb2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_472ba386-1fe0-4a9e-974d-afcf0829e2ab" xlink:to="loc_srt_RangeMember_320eebdf-04a3-4561-b0e2-9a2af2a61bb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_3c78b853-f114-47ef-a075-92b666b08c19" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_320eebdf-04a3-4561-b0e2-9a2af2a61bb2" xlink:to="loc_srt_MinimumMember_3c78b853-f114-47ef-a075-92b666b08c19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1fc3a486-536d-46f2-80fb-062506806173" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_320eebdf-04a3-4561-b0e2-9a2af2a61bb2" xlink:to="loc_srt_MaximumMember_1fc3a486-536d-46f2-80fb-062506806173" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_737e41b2-0c4c-47b2-a38b-dd26d7a9dafd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyClaimsDismissedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_737e41b2-0c4c-47b2-a38b-dd26d7a9dafd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_ee291035-6ee6-45e3-86a2-93ec44f1e3b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_DebtInstrumentTerm_ee291035-6ee6-45e3-86a2-93ec44f1e3b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b1d4064f-cd69-419b-960e-c6e93d874833" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b1d4064f-cd69-419b-960e-c6e93d874833" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_e09a17fe-a16f-426c-83bc-3b7aeda5e98d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_e09a17fe-a16f-426c-83bc-3b7aeda5e98d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LineOfCreditFacilityPenaltiesDue_a5e69709-7312-4706-afeb-89aa6b1111d9" xlink:href="tw-20240630.xsd#tw_LineOfCreditFacilityPenaltiesDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_LineOfCreditFacilityPenaltiesDue_a5e69709-7312-4706-afeb-89aa6b1111d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LineOfCreditFacilityTerminationPenalties_7647a4b9-cbcd-465e-97af-f0e91b980f3b" xlink:href="tw-20240630.xsd#tw_LineOfCreditFacilityTerminationPenalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_LineOfCreditFacilityTerminationPenalties_7647a4b9-cbcd-465e-97af-f0e91b980f3b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LineOfCreditFacilityAccordionFeatureIncreaseLimit_b93a97d2-9537-4f96-8640-09fae361e6e1" xlink:href="tw-20240630.xsd#tw_LineOfCreditFacilityAccordionFeatureIncreaseLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_LineOfCreditFacilityAccordionFeatureIncreaseLimit_b93a97d2-9537-4f96-8640-09fae361e6e1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_87517d03-9900-4126-aa75-54ed5d2d89df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_87517d03-9900-4126-aa75-54ed5d2d89df" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e956953b-d9cc-4875-89ac-69a3155afd9f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e956953b-d9cc-4875-89ac-69a3155afd9f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DebtInstrumentCreditAdjustmentSpread_8723b3da-d100-4212-bab8-9ce7828806d7" xlink:href="tw-20240630.xsd#tw_DebtInstrumentCreditAdjustmentSpread"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_DebtInstrumentCreditAdjustmentSpread_8723b3da-d100-4212-bab8-9ce7828806d7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DebtInstrumentAdjustmentInAdditionToCreditAdjustmentSpread_98300972-903f-47c1-a441-b2df8ce0580e" xlink:href="tw-20240630.xsd#tw_DebtInstrumentAdjustmentInAdditionToCreditAdjustmentSpread"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_DebtInstrumentAdjustmentInAdditionToCreditAdjustmentSpread_98300972-903f-47c1-a441-b2df8ce0580e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DebtInstrumentFloorRate_6c3a863f-388d-4485-bd20-3789a870a88f" xlink:href="tw-20240630.xsd#tw_DebtInstrumentFloorRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_tw_DebtInstrumentFloorRate_6c3a863f-388d-4485-bd20-3789a870a88f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_acdc91c7-0adc-400e-932a-f01d5d7fba48" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_acdc91c7-0adc-400e-932a-f01d5d7fba48" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_e5b82cf1-fcd5-41b0-8206-fe158e53874d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_12ee0289-0465-4af1-a213-4899f04a5b6d" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_e5b82cf1-fcd5-41b0-8206-fe158e53874d" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/EarningsPerShareScheduleofBasicandDilutedEarningsPerShareDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#EarningsPerShareScheduleofBasicandDilutedEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/EarningsPerShareScheduleofBasicandDilutedEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasicLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_da9c8159-41c0-4a61-b902-a01e34cd3df5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_da9c8159-41c0-4a61-b902-a01e34cd3df5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_acd98f88-215b-4a55-9d30-1e0146d7c1a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_da9c8159-41c0-4a61-b902-a01e34cd3df5" xlink:to="loc_us-gaap_AwardTypeAxis_acd98f88-215b-4a55-9d30-1e0146d7c1a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_acd98f88-215b-4a55-9d30-1e0146d7c1a5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_acd98f88-215b-4a55-9d30-1e0146d7c1a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_acd98f88-215b-4a55-9d30-1e0146d7c1a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_acd98f88-215b-4a55-9d30-1e0146d7c1a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_4ceba239-0be8-40e0-86d5-1bcca1d5363f" xlink:href="tw-20240630.xsd#tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:to="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_4ceba239-0be8-40e0-86d5-1bcca1d5363f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_3f860fa2-9984-4e49-9a46-7f8116684c55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:to="loc_us-gaap_EmployeeStockOptionMember_3f860fa2-9984-4e49-9a46-7f8116684c55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_f0e831e7-96ec-4ec3-a295-4e590a8c682a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_f0e831e7-96ec-4ec3-a295-4e590a8c682a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_b7650273-ca3a-4ada-84bb-95645b57dccf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_500f1ad7-4f06-40cf-8d76-5dd52e5871f4" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_b7650273-ca3a-4ada-84bb-95645b57dccf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_71c5dc98-1bab-4f43-8d3e-e812eb81ea30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:to="loc_us-gaap_NetIncomeLoss_71c5dc98-1bab-4f43-8d3e-e812eb81ea30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_5873c4ea-be3a-492a-a138-c8d3d3b8bc15" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:to="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_5873c4ea-be3a-492a-a138-c8d3d3b8bc15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_044b9563-5755-4b9d-be6c-b9060284cc89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_044b9563-5755-4b9d-be6c-b9060284cc89" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_cc52015b-65a4-4cec-bcfe-15a7f3523ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_8723d460-c21a-4d15-be3e-5b8e70d131f8" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_cc52015b-65a4-4cec-bcfe-15a7f3523ca1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_10027239-7738-4a9b-96d9-fedad5e1224c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_10027239-7738-4a9b-96d9-fedad5e1224c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_351f9a4e-9c7a-490d-804e-5a3097a45538" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_10027239-7738-4a9b-96d9-fedad5e1224c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_351f9a4e-9c7a-490d-804e-5a3097a45538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_8053cddc-c606-413b-8548-919e17162f6a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_10027239-7738-4a9b-96d9-fedad5e1224c" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_8053cddc-c606-413b-8548-919e17162f6a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_725791fa-8dd0-41eb-abf9-9a678bb74a46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_10027239-7738-4a9b-96d9-fedad5e1224c" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_725791fa-8dd0-41eb-abf9-9a678bb74a46" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_a8e5701e-1341-4749-b722-d3c3ca3b34d8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_us-gaap_EarningsPerShareBasic_a8e5701e-1341-4749-b722-d3c3ca3b34d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_fa626711-49b0-4628-b32e-efaeb69efff0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_us-gaap_EarningsPerShareDiluted_fa626711-49b0-4628-b32e-efaeb69efff0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares_ce44eae7-1fc6-4040-9855-dd7cd1e995b0" xlink:href="tw-20240630.xsd#tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_c2e41dce-4e29-49d7-922f-f0445199581a" xlink:to="loc_tw_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossShares_ce44eae7-1fc6-4040-9855-dd7cd1e995b0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/EarningsPerShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofEarningsPerShareDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#EarningsPerShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/EarningsPerShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52506d96-f94a-4cec-80c7-cdb2eec16d81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7a3ff311-a3ae-4880-9b64-0e6164f91f91" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52506d96-f94a-4cec-80c7-cdb2eec16d81" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7a3ff311-a3ae-4880-9b64-0e6164f91f91" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_976dada3-b79f-4f21-a41f-9e1e2c295d03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7a3ff311-a3ae-4880-9b64-0e6164f91f91" xlink:to="loc_us-gaap_AwardTypeAxis_976dada3-b79f-4f21-a41f-9e1e2c295d03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_976dada3-b79f-4f21-a41f-9e1e2c295d03_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_976dada3-b79f-4f21-a41f-9e1e2c295d03" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_976dada3-b79f-4f21-a41f-9e1e2c295d03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_976dada3-b79f-4f21-a41f-9e1e2c295d03" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_56068199-943e-429b-8dd5-16269ae34e0c" xlink:href="tw-20240630.xsd#tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:to="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_56068199-943e-429b-8dd5-16269ae34e0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_dcbd13bb-4325-4cf1-b37e-27686e98cc55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:to="loc_us-gaap_EmployeeStockOptionMember_dcbd13bb-4325-4cf1-b37e-27686e98cc55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_07e9490a-ff44-4dda-a6f1-abc969646b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_07e9490a-ff44-4dda-a6f1-abc969646b4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_62d41db6-d384-4e3a-932b-614a63946717" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_62d41db6-d384-4e3a-932b-614a63946717" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LimitedLiabilityCompanyUnitsMember_1e7e18bc-b7cd-426e-bcbe-0883cf692da3" xlink:href="tw-20240630.xsd#tw_LimitedLiabilityCompanyUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c314b05a-9c4c-4c5d-9a06-6e0dbabe7c09" xlink:to="loc_tw_LimitedLiabilityCompanyUnitsMember_1e7e18bc-b7cd-426e-bcbe-0883cf692da3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_d165a68d-5ae5-4154-8bf4-c39e0e412e19" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52506d96-f94a-4cec-80c7-cdb2eec16d81" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_d165a68d-5ae5-4154-8bf4-c39e0e412e19" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/RegulatoryCapitalRequirementsScheduleofRegulatoryCapitalRequirementsandScheduleofRegulatoryCapitalRequirementsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#RegulatoryCapitalRequirementsScheduleofRegulatoryCapitalRequirementsandScheduleofRegulatoryCapitalRequirementsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/RegulatoryCapitalRequirementsScheduleofRegulatoryCapitalRequirementsandScheduleofRegulatoryCapitalRequirementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_d4715b26-a3bf-48e8-992a-5d0593a3c12e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_0d72831e-e473-40ba-bca0-88416b49c8ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_d4715b26-a3bf-48e8-992a-5d0593a3c12e" xlink:to="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_0d72831e-e473-40ba-bca0-88416b49c8ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_5de28e1b-a159-4730-9a24-88b5d4edad43" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_0d72831e-e473-40ba-bca0-88416b49c8ee" xlink:to="loc_srt_ConsolidatedEntitiesAxis_5de28e1b-a159-4730-9a24-88b5d4edad43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_5de28e1b-a159-4730-9a24-88b5d4edad43_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_5de28e1b-a159-4730-9a24-88b5d4edad43" xlink:to="loc_srt_ConsolidatedEntitiesDomain_5de28e1b-a159-4730-9a24-88b5d4edad43_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_5de28e1b-a159-4730-9a24-88b5d4edad43" xlink:to="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebLlcMember_2af847ce-6862-44e3-918e-470f3694dbe6" xlink:href="tw-20240630.xsd#tw_TradewebLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebLlcMember_2af847ce-6862-44e3-918e-470f3694dbe6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DealerwebMember_9e143067-1bbd-43be-b969-9a14dafe9747" xlink:href="tw-20240630.xsd#tw_DealerwebMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_DealerwebMember_9e143067-1bbd-43be-b969-9a14dafe9747" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebDirectLlcMember_2e64a6d5-c9af-4b4c-887c-309acb24242f" xlink:href="tw-20240630.xsd#tw_TradewebDirectLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebDirectLlcMember_2e64a6d5-c9af-4b4c-887c-309acb24242f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebEuropeLimitedMember_8aa58864-293a-4e7b-a4a6-21ebac65e3cf" xlink:href="tw-20240630.xsd#tw_TradewebEuropeLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebEuropeLimitedMember_8aa58864-293a-4e7b-a4a6-21ebac65e3cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebJapanKkMember_bc149e66-2cff-4db5-abce-f69ed0eb89fa" xlink:href="tw-20240630.xsd#tw_TradewebJapanKkMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebJapanKkMember_bc149e66-2cff-4db5-abce-f69ed0eb89fa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebEuBvMember_3e588278-8fda-4bc9-9354-3448360deb10" xlink:href="tw-20240630.xsd#tw_TradewebEuBvMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebEuBvMember_3e588278-8fda-4bc9-9354-3448360deb10" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebExecutionServicesLimitedMember_fff459f6-9c7d-4247-9072-746a860654bf" xlink:href="tw-20240630.xsd#tw_TradewebExecutionServicesLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebExecutionServicesLimitedMember_fff459f6-9c7d-4247-9072-746a860654bf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TradewebExecutionServicesBVMember_bc015a8c-12db-4ec4-8663-c6703d79bfe8" xlink:href="tw-20240630.xsd#tw_TradewebExecutionServicesBVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TradewebExecutionServicesBVMember_bc015a8c-12db-4ec4-8663-c6703d79bfe8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_YieldbrokerMember_b29ffa45-e6bd-4508-bd2a-507abd40b1ac" xlink:href="tw-20240630.xsd#tw_YieldbrokerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_YieldbrokerMember_b29ffa45-e6bd-4508-bd2a-507abd40b1ac" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TDIFCMember_5d8c2337-f0fa-4108-9f61-db5af34d743a" xlink:href="tw-20240630.xsd#tw_TDIFCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TDIFCMember_5d8c2337-f0fa-4108-9f61-db5af34d743a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TwSefLlcMember_8a0360a9-5e51-4ccd-a4e4-99a2239995df" xlink:href="tw-20240630.xsd#tw_TwSefLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_TwSefLlcMember_8a0360a9-5e51-4ccd-a4e4-99a2239995df" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DwSefLlcMember_fbbaa0be-1c13-4d0f-9f18-3b0c69a21636" xlink:href="tw-20240630.xsd#tw_DwSefLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_939e3765-6a12-4cf0-8bda-434a768e89e1" xlink:to="loc_tw_DwSefLlcMember_fbbaa0be-1c13-4d0f-9f18-3b0c69a21636" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RegulatoryCapital_16b2257f-e010-4776-bdbe-ee7142b1f56f" xlink:href="tw-20240630.xsd#tw_RegulatoryCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_d4715b26-a3bf-48e8-992a-5d0593a3c12e" xlink:to="loc_tw_RegulatoryCapital_16b2257f-e010-4776-bdbe-ee7142b1f56f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RegulatoryCapitalRequirement_ca2d5b6c-21ca-43c2-bdac-1c40f9c71b0d" xlink:href="tw-20240630.xsd#tw_RegulatoryCapitalRequirement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_RegulatoryCapital_16b2257f-e010-4776-bdbe-ee7142b1f56f" xlink:to="loc_tw_RegulatoryCapitalRequirement_ca2d5b6c-21ca-43c2-bdac-1c40f9c71b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ExcessRegulatoryCapital_22c09255-0cad-4d9d-9eb3-c7d310b8fa50" xlink:href="tw-20240630.xsd#tw_ExcessRegulatoryCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_RegulatoryCapital_16b2257f-e010-4776-bdbe-ee7142b1f56f" xlink:to="loc_tw_ExcessRegulatoryCapital_22c09255-0cad-4d9d-9eb3-c7d310b8fa50" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NetCapitalUnderCommodityExchangeActComputation_233d36fa-b483-44dc-80b1-d0e1fa6a3bfe" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NetCapitalUnderCommodityExchangeActComputation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_d4715b26-a3bf-48e8-992a-5d0593a3c12e" xlink:to="loc_srt_NetCapitalUnderCommodityExchangeActComputation_233d36fa-b483-44dc-80b1-d0e1fa6a3bfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RequiredNetCapitalUnderCommodityExchangeAct1_8dcef9e4-82f6-4799-a7a5-f95eaac95360" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RequiredNetCapitalUnderCommodityExchangeAct1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NetCapitalUnderCommodityExchangeActComputation_233d36fa-b483-44dc-80b1-d0e1fa6a3bfe" xlink:to="loc_srt_RequiredNetCapitalUnderCommodityExchangeAct1_8dcef9e4-82f6-4799-a7a5-f95eaac95360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NetCapitalExcessShortageUnderCommodityExchangeAct_a2904e6b-3e9d-4130-a2ad-fe6a87eefaaf" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NetCapitalExcessShortageUnderCommodityExchangeAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NetCapitalUnderCommodityExchangeActComputation_233d36fa-b483-44dc-80b1-d0e1fa6a3bfe" xlink:to="loc_srt_NetCapitalExcessShortageUnderCommodityExchangeAct_a2904e6b-3e9d-4130-a2ad-fe6a87eefaaf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LiquidFinancialAssets_57678bc0-b4d7-4bba-b610-679f1c64f1d2" xlink:href="tw-20240630.xsd#tw_LiquidFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_d4715b26-a3bf-48e8-992a-5d0593a3c12e" xlink:to="loc_tw_LiquidFinancialAssets_57678bc0-b4d7-4bba-b610-679f1c64f1d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RequiredLiquidFinancialAssets_a7e96c9b-6523-4ced-aeb6-9ffd53034c5c" xlink:href="tw-20240630.xsd#tw_RequiredLiquidFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_LiquidFinancialAssets_57678bc0-b4d7-4bba-b610-679f1c64f1d2" xlink:to="loc_tw_RequiredLiquidFinancialAssets_a7e96c9b-6523-4ced-aeb6-9ffd53034c5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_ExcessLiquidFinancialAssets_289b4173-e994-40f7-98fd-b2db8799c39c" xlink:href="tw-20240630.xsd#tw_ExcessLiquidFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tw_LiquidFinancialAssets_57678bc0-b4d7-4bba-b610-679f1c64f1d2" xlink:to="loc_tw_ExcessLiquidFinancialAssets_289b4173-e994-40f7-98fd-b2db8799c39c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/BusinessSegmentandGeographicInformationScheduleofInformationRegardingRevenuebyClientSectorDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#BusinessSegmentandGeographicInformationScheduleofInformationRegardingRevenuebyClientSectorDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/BusinessSegmentandGeographicInformationScheduleofInformationRegardingRevenuebyClientSectorDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_ff22d350-32cd-4d30-8849-2e6b6df00b26" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_e88728d7-8573-4ec0-9e4d-0bee371747f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ff22d350-32cd-4d30-8849-2e6b6df00b26" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_e88728d7-8573-4ec0-9e4d-0bee371747f5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_be74c22f-9528-4a26-9025-09ff3a6dcde5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_e88728d7-8573-4ec0-9e4d-0bee371747f5" xlink:to="loc_srt_MajorCustomersAxis_be74c22f-9528-4a26-9025-09ff3a6dcde5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_be74c22f-9528-4a26-9025-09ff3a6dcde5_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_be74c22f-9528-4a26-9025-09ff3a6dcde5" xlink:to="loc_srt_NameOfMajorCustomerDomain_be74c22f-9528-4a26-9025-09ff3a6dcde5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_be74c22f-9528-4a26-9025-09ff3a6dcde5" xlink:to="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_InstitutionalClientSectorMember_03f9a2cd-0fb0-4c5f-be5b-da58eec605f4" xlink:href="tw-20240630.xsd#tw_InstitutionalClientSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:to="loc_tw_InstitutionalClientSectorMember_03f9a2cd-0fb0-4c5f-be5b-da58eec605f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_WholesaleClientSectorMember_fa6ba37c-860f-45c3-944a-16a6fd9af156" xlink:href="tw-20240630.xsd#tw_WholesaleClientSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:to="loc_tw_WholesaleClientSectorMember_fa6ba37c-860f-45c3-944a-16a6fd9af156" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_RetailClientSectorMember_0a612902-c933-4a5e-93b8-533ba8e535e2" xlink:href="tw-20240630.xsd#tw_RetailClientSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:to="loc_tw_RetailClientSectorMember_0a612902-c933-4a5e-93b8-533ba8e535e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_MarketDataClientSectorMember_8b05e942-3390-4c70-a70f-b273d80b76ee" xlink:href="tw-20240630.xsd#tw_MarketDataClientSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_f6d947d4-6b22-4f62-a54d-3dcfe68474b4" xlink:to="loc_tw_MarketDataClientSectorMember_8b05e942-3390-4c70-a70f-b273d80b76ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_078ed618-532f-4938-85b8-f59969f3ec90" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ff22d350-32cd-4d30-8849-2e6b6df00b26" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_078ed618-532f-4938-85b8-f59969f3ec90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_1a5939ca-c3eb-4e16-ae6c-db63b3c3efce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ff22d350-32cd-4d30-8849-2e6b6df00b26" xlink:to="loc_us-gaap_CostsAndExpenses_1a5939ca-c3eb-4e16-ae6c-db63b3c3efce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_e01ec9f4-7384-4bc6-95f4-3082b2cc46ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ff22d350-32cd-4d30-8849-2e6b6df00b26" xlink:to="loc_us-gaap_OperatingIncomeLoss_e01ec9f4-7384-4bc6-95f4-3082b2cc46ee" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/BusinessSegmentandGeographicInformationScheduleofRevenueandLongLivedAssetsbyGeographicLocationDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#BusinessSegmentandGeographicInformationScheduleofRevenueandLongLivedAssetsbyGeographicLocationDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/BusinessSegmentandGeographicInformationScheduleofRevenueandLongLivedAssetsbyGeographicLocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_050d9a14-5063-4fd4-be1f-81a28713536b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_d7e16087-6ed7-4575-bdc1-62a0283e253f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_050d9a14-5063-4fd4-be1f-81a28713536b" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_d7e16087-6ed7-4575-bdc1-62a0283e253f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_5071cfc7-dbc0-4d3f-964b-6bd05e378d39" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_d7e16087-6ed7-4575-bdc1-62a0283e253f" xlink:to="loc_srt_StatementGeographicalAxis_5071cfc7-dbc0-4d3f-964b-6bd05e378d39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_5071cfc7-dbc0-4d3f-964b-6bd05e378d39_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_5071cfc7-dbc0-4d3f-964b-6bd05e378d39" xlink:to="loc_srt_SegmentGeographicalDomain_5071cfc7-dbc0-4d3f-964b-6bd05e378d39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_d47b7237-ab82-4e26-a946-cdeafd4813f2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_5071cfc7-dbc0-4d3f-964b-6bd05e378d39" xlink:to="loc_srt_SegmentGeographicalDomain_d47b7237-ab82-4e26-a946-cdeafd4813f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_1a0f06af-3c6d-4e88-b143-8f56c4b3cd59" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d47b7237-ab82-4e26-a946-cdeafd4813f2" xlink:to="loc_country_US_1a0f06af-3c6d-4e88-b143-8f56c4b3cd59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_6ca13fe4-9941-4ab7-a7e3-64939eb16e1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d47b7237-ab82-4e26-a946-cdeafd4813f2" xlink:to="loc_us-gaap_NonUsMember_6ca13fe4-9941-4ab7-a7e3-64939eb16e1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_a9fd6847-717a-4451-a541-7f65c13298e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_050d9a14-5063-4fd4-be1f-81a28713536b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_a9fd6847-717a-4451-a541-7f65c13298e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_93ef142a-250e-47f7-a904-1cb3d687a497" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_050d9a14-5063-4fd4-be1f-81a28713536b" xlink:to="loc_us-gaap_NoncurrentAssets_93ef142a-250e-47f7-a904-1cb3d687a497" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.tradeweb.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="tw-20240630.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.tradeweb.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_18156f92-a6ac-4c49-9046-c7b58fb8823a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_b9dd9afd-2c23-4d6c-85f8-e45671fe157f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_18156f92-a6ac-4c49-9046-c7b58fb8823a" xlink:to="loc_us-gaap_SubsequentEventTable_b9dd9afd-2c23-4d6c-85f8-e45671fe157f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_e4d485cb-5455-4db7-a4f9-1bea029fe5c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_b9dd9afd-2c23-4d6c-85f8-e45671fe157f" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_e4d485cb-5455-4db7-a4f9-1bea029fe5c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e4d485cb-5455-4db7-a4f9-1bea029fe5c4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_e4d485cb-5455-4db7-a4f9-1bea029fe5c4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e4d485cb-5455-4db7-a4f9-1bea029fe5c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_a58ce271-acca-451c-887a-57aa5fcad041" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_e4d485cb-5455-4db7-a4f9-1bea029fe5c4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_a58ce271-acca-451c-887a-57aa5fcad041" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_e5825449-352a-48c1-8bf1-646e642dddf3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_a58ce271-acca-451c-887a-57aa5fcad041" xlink:to="loc_us-gaap_SubsequentEventMember_e5825449-352a-48c1-8bf1-646e642dddf3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8acad337-4fa7-415c-8f05-b57fbb2a2fa2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_b9dd9afd-2c23-4d6c-85f8-e45671fe157f" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8acad337-4fa7-415c-8f05-b57fbb2a2fa2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8acad337-4fa7-415c-8f05-b57fbb2a2fa2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8acad337-4fa7-415c-8f05-b57fbb2a2fa2" xlink:to="loc_us-gaap_ClassOfStockDomain_8acad337-4fa7-415c-8f05-b57fbb2a2fa2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c16ee68d-a772-490b-84d2-15048aa3fcd9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8acad337-4fa7-415c-8f05-b57fbb2a2fa2" xlink:to="loc_us-gaap_ClassOfStockDomain_c16ee68d-a772-490b-84d2-15048aa3fcd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_297aa5f9-ebc9-4289-8277-2bde8e522940" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c16ee68d-a772-490b-84d2-15048aa3fcd9" xlink:to="loc_us-gaap_CommonClassAMember_297aa5f9-ebc9-4289-8277-2bde8e522940" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_997a050f-11dd-4018-87ac-936449cd71d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c16ee68d-a772-490b-84d2-15048aa3fcd9" xlink:to="loc_us-gaap_CommonClassBMember_997a050f-11dd-4018-87ac-936449cd71d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_efc9a271-8ba0-4a69-8f05-d68d09eee311" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_b9dd9afd-2c23-4d6c-85f8-e45671fe157f" xlink:to="loc_dei_LegalEntityAxis_efc9a271-8ba0-4a69-8f05-d68d09eee311" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_efc9a271-8ba0-4a69-8f05-d68d09eee311_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_efc9a271-8ba0-4a69-8f05-d68d09eee311" xlink:to="loc_dei_EntityDomain_efc9a271-8ba0-4a69-8f05-d68d09eee311_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_30878c5e-4c5e-48be-ab1a-87da0dfec2af" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_efc9a271-8ba0-4a69-8f05-d68d09eee311" xlink:to="loc_dei_EntityDomain_30878c5e-4c5e-48be-ab1a-87da0dfec2af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_TWMLLCMember_b423fccf-e7b1-4973-9fa1-6ad8c9fe602d" xlink:href="tw-20240630.xsd#tw_TWMLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_30878c5e-4c5e-48be-ab1a-87da0dfec2af" xlink:to="loc_tw_TWMLLCMember_b423fccf-e7b1-4973-9fa1-6ad8c9fe602d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_cab19ae4-abc1-4401-bfb2-88d5f115bb8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_18156f92-a6ac-4c49-9046-c7b58fb8823a" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_cab19ae4-abc1-4401-bfb2-88d5f115bb8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_0d4a2587-c774-45aa-860a-32b116be3771" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_18156f92-a6ac-4c49-9046-c7b58fb8823a" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_0d4a2587-c774-45aa-860a-32b116be3771" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_Omnibus2019EquityIncentivePlanMember_a422f8fb-75ec-46e6-a015-a9c5f032bd71" xlink:href="tw-20240630.xsd#tw_Omnibus2019EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_tw_Omnibus2019EquityIncentivePlanMember_a422f8fb-75ec-46e6-a015-a9c5f032bd71" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_2d2fe296-90fd-4bec-b87d-115bc5f911b1" xlink:href="tw-20240630.xsd#tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_tw_EquitySettledPerformanceBasedRestrictedStockUnitsMember_2d2fe296-90fd-4bec-b87d-115bc5f911b1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_LimitedLiabilityCompanyUnitsMember_17891eeb-b7ce-44f2-8f91-269339621003" xlink:href="tw-20240630.xsd#tw_LimitedLiabilityCompanyUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_tw_LimitedLiabilityCompanyUnitsMember_17891eeb-b7ce-44f2-8f91-269339621003" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#TradingArrangmentsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllTradingArrangementsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllTradingArrangementsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyAwardedPerformanceBasedRestrictedStockUnitsMember_8ff498d0-d6e9-4c44-8cad-268966d2d9c8" xlink:href="tw-20240630.xsd#tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyAwardedPerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="loc_tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyAwardedPerformanceBasedRestrictedStockUnitsMember_8ff498d0-d6e9-4c44-8cad-268966d2d9c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DouglasFriedmanTradingArrangementPerformanceBasedRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughJanuary12025Member_777e27b9-9274-4cc2-be91-3cf84fd256cc" xlink:href="tw-20240630.xsd#tw_DouglasFriedmanTradingArrangementPerformanceBasedRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughJanuary12025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="loc_tw_DouglasFriedmanTradingArrangementPerformanceBasedRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughJanuary12025Member_777e27b9-9274-4cc2-be91-3cf84fd256cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyRestrictedStockUnitsMember_ecc9fbff-b64d-4f31-9391-eac17ca50341" xlink:href="tw-20240630.xsd#tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="loc_tw_DouglasFriedmanTradingArrangementVestingOfPreviouslyRestrictedStockUnitsMember_ecc9fbff-b64d-4f31-9391-eac17ca50341" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DouglasFriedmanTradingArrangementRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughMarch152025Member_bd6af6b3-6567-4fc6-a6c0-43befd3fe2a6" xlink:href="tw-20240630.xsd#tw_DouglasFriedmanTradingArrangementRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughMarch152025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="loc_tw_DouglasFriedmanTradingArrangementRestrictedStockUnitsAccruedDuringVestingPeriodOfMarch152022ThroughMarch152025Member_bd6af6b3-6567-4fc6-a6c0-43befd3fe2a6" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_tw_DouglasFriedmanMember_4d276b66-7a4b-4116-a4a4-83230348af7a" xlink:href="tw-20240630.xsd#tw_DouglasFriedmanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_tw_DouglasFriedmanMember_4d276b66-7a4b-4116-a4a4-83230348af7a" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
