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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e4c07-9c8f-7973-bb51-1d8dcff9d2d5,g:19cbf5e3-8b82-4cfa-ad01-2fcb144aa4bb-->
<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://customersbank.com/role/Cover" xlink:type="simple" xlink:href="cubi-20260630.xsd#Cover"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_019e4c07-a612-71c8-9288-2dfd3f9aeaed" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntitiesTable_019e4c07-a612-71c8-9288-2dfd3f9aeaed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a612-794d-a750-00fe074d6fd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_019e4c07-a612-71c8-9288-2dfd3f9aeaed" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a612-794d-a750-00fe074d6fd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-794d-a750-00fe074d6fd7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a612-794d-a750-00fe074d6fd7" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-794d-a750-00fe074d6fd7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-7c9b-aa08-fdf94c8147e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a612-794d-a750-00fe074d6fd7" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-7c9b-aa08-fdf94c8147e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e4c07-a612-7db7-a7a0-86883a0caa5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-7c9b-aa08-fdf94c8147e8" xlink:to="loc_us-gaap_CommonStockMember_019e4c07-a612-7db7-a7a0-86883a0caa5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesFPreferredStockMember_019e4c07-a612-7d7f-9bfb-d44d7f5aa62f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesFPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-7c9b-aa08-fdf94c8147e8" xlink:to="loc_us-gaap_SeriesFPreferredStockMember_019e4c07-a612-7d7f-9bfb-d44d7f5aa62f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebtMember_019e4c07-a612-7838-a832-f33988dd6b0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubordinatedDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a612-7c9b-aa08-fdf94c8147e8" xlink:to="loc_us-gaap_SubordinatedDebtMember_019e4c07-a612-7838-a832-f33988dd6b0f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019e4c07-a612-7f2a-9e78-eaf3efb0e36b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentType_019e4c07-a612-7f2a-9e78-eaf3efb0e36b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019e4c07-a612-7cf4-bed5-36bbd5a9725a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentQuarterlyReport_019e4c07-a612-7cf4-bed5-36bbd5a9725a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019e4c07-a612-7e68-817f-c60474cb78f1" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentPeriodEndDate_019e4c07-a612-7e68-817f-c60474cb78f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019e4c07-a612-7f91-bc75-e2980ef226bc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentTransitionReport_019e4c07-a612-7f91-bc75-e2980ef226bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019e4c07-a612-7f0a-8934-4b2bef204889" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityFileNumber_019e4c07-a612-7f0a-8934-4b2bef204889" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019e4c07-a612-7518-a05f-ecd26b8bfd7a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityRegistrantName_019e4c07-a612-7518-a05f-ecd26b8bfd7a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019e4c07-a612-79fb-ba98-8dbcd1f7c5d4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019e4c07-a612-79fb-ba98-8dbcd1f7c5d4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019e4c07-a612-7d58-ae2e-717595079718" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityTaxIdentificationNumber_019e4c07-a612-7d58-ae2e-717595079718" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019e4c07-a612-7784-b703-f9c8aa1c2725" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityAddressAddressLine1_019e4c07-a612-7784-b703-f9c8aa1c2725" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019e4c07-a612-7ade-86db-4c155de6aec5" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityAddressCityOrTown_019e4c07-a612-7ade-86db-4c155de6aec5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019e4c07-a612-70a9-b075-e05b67b18400" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityAddressStateOrProvince_019e4c07-a612-70a9-b075-e05b67b18400" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019e4c07-a612-78f1-8ad2-1007f7821702" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityAddressPostalZipCode_019e4c07-a612-78f1-8ad2-1007f7821702" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019e4c07-a612-783a-b3d9-cd921ba9ea9b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_CityAreaCode_019e4c07-a612-783a-b3d9-cd921ba9ea9b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019e4c07-a612-734e-b425-c0f778200902" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_LocalPhoneNumber_019e4c07-a612-734e-b425-c0f778200902" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019e4c07-a612-79ab-b210-3fa614b97c39" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_Security12bTitle_019e4c07-a612-79ab-b210-3fa614b97c39" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019e4c07-a612-7bc5-9fc5-178bf770f0e3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_TradingSymbol_019e4c07-a612-7bc5-9fc5-178bf770f0e3" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019e4c07-a612-7771-b8a4-12207a907d20" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_SecurityExchangeName_019e4c07-a612-7771-b8a4-12207a907d20" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019e4c07-a612-7226-85d4-3f30e35b6ece" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityCurrentReportingStatus_019e4c07-a612-7226-85d4-3f30e35b6ece" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019e4c07-a612-7ab5-afcc-7a06b30a90e4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityInteractiveDataCurrent_019e4c07-a612-7ab5-afcc-7a06b30a90e4" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019e4c07-a612-70e6-a210-254a9840131b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityFilerCategory_019e4c07-a612-70e6-a210-254a9840131b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019e4c07-a612-7f03-a5b5-ceee9362e432" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntitySmallBusiness_019e4c07-a612-7f03-a5b5-ceee9362e432" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019e4c07-a612-7ab6-a39a-947fa35af53b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityEmergingGrowthCompany_019e4c07-a612-7ab6-a39a-947fa35af53b" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019e4c07-a612-7322-8dca-13b5683ce0e7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityShellCompany_019e4c07-a612-7322-8dca-13b5683ce0e7" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019e4c07-a612-74bc-aefe-957cc393ebd0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019e4c07-a612-74bc-aefe-957cc393ebd0" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019e4c07-a612-71f6-9615-735b9e757ad0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_AmendmentFlag_019e4c07-a612-71f6-9615-735b9e757ad0" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019e4c07-a612-79cb-ab2d-5dc66ab36075" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentFiscalYearFocus_019e4c07-a612-79cb-ab2d-5dc66ab36075" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019e4c07-a612-7bfd-b584-523338c7e2b9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019e4c07-a612-7bfd-b584-523338c7e2b9" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019e4c07-a612-7968-8186-137e9907660c" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_EntityCentralIndexKey_019e4c07-a612-7968-8186-137e9907660c" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019e4c07-a612-71f4-8f42-8a11cc96b82e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e4c07-a612-7485-8c2e-68e084da49ae" xlink:to="loc_dei_CurrentFiscalYearEndDate_019e4c07-a612-71f4-8f42-8a11cc96b82e" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITED" xlink:type="simple" xlink:href="cubi-20260630.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITED"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e4c07-a613-7c6b-9499-08afd5a9c533" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e4c07-a613-73fa-a4ee-d24c3b6fe675" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e4c07-a613-7c6b-9499-08afd5a9c533" xlink:to="loc_us-gaap_StatementTable_019e4c07-a613-73fa-a4ee-d24c3b6fe675" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-7b37-af28-2601dedb43ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e4c07-a613-73fa-a4ee-d24c3b6fe675" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-7b37-af28-2601dedb43ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7b37-af28-2601dedb43ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-7b37-af28-2601dedb43ca" xlink:to="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7b37-af28-2601dedb43ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-7b37-af28-2601dedb43ca" xlink:to="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_019e4c07-a613-7d5d-8b32-4fa5327f1124" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_PreferredStockMember_019e4c07-a613-7d5d-8b32-4fa5327f1124" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e4c07-a613-76f5-9f2e-c58d68bd1ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_CommonStockMember_019e4c07-a613-76f5-9f2e-c58d68bd1ac4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e4c07-a613-783d-8590-6ddd67e2a4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e4c07-a613-783d-8590-6ddd67e2a4e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e4c07-a613-78ed-91b4-3b480f506d4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_RetainedEarningsMember_019e4c07-a613-78ed-91b4-3b480f506d4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-7268-8227-24c93ff2fa0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-7268-8227-24c93ff2fa0a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019e4c07-a613-71cd-8981-fd155c22e8fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-7e9d-83b6-5aab074ce672" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019e4c07-a613-71cd-8981-fd155c22e8fa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e4c07-a613-7c6b-9499-08afd5a9c533" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019e4c07-a613-7273-ac00-df03b2604aea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019e4c07-a613-7273-ac00-df03b2604aea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e4c07-a613-7a3d-943d-73999ab72551" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockholdersEquity_019e4c07-a613-7a3d-943d-73999ab72551" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e4c07-a613-7b2d-85cb-feb93ded7a44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e4c07-a613-7b2d-85cb-feb93ded7a44" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e4c07-a613-7e14-a62a-5eec9d508012" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_NetIncomeLoss_019e4c07-a613-7e14-a62a-5eec9d508012" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e4c07-a613-753d-8f4f-38e05beb83e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e4c07-a613-753d-8f4f-38e05beb83e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStock_019e4c07-a613-75c4-8b33-aa926eb01e62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_DividendsPreferredStock_019e4c07-a613-75c4-8b33-aa926eb01e62" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_019ed0e2-2aa3-7edc-991f-fdf60647e4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_019ed0e2-2aa3-7edc-991f-fdf60647e4e5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_019ed0e2-2aa3-7ffd-b727-e22d37862125" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_019ed0e2-2aa3-7ffd-b727-e22d37862125" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_WriteOffOfStockIssuanceCostsPreferredStock_019ed0e2-930e-76ca-89ae-46e0256f5499" xlink:href="cubi-20260630.xsd#cubi_WriteOffOfStockIssuanceCostsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_cubi_WriteOffOfStockIssuanceCostsPreferredStock_019ed0e2-930e-76ca-89ae-46e0256f5499" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e4c07-a613-7a30-8829-1d80f350f928" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e4c07-a613-7a30-8829-1d80f350f928" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e4c07-a613-768d-a533-a162913a8b9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e4c07-a613-768d-a533-a162913a8b9e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e4c07-a613-7fa6-8858-5b7f072ed7dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e4c07-a613-7fa6-8858-5b7f072ed7dd" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019e4c07-a613-7a9d-ab67-c3f86a52213c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019e4c07-a613-7a9d-ab67-c3f86a52213c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e4c07-a613-73b5-abc2-7000ee570f8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e4c07-a613-7760-b24e-232cf30a2268" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e4c07-a613-73b5-abc2-7000ee570f8c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019e4c07-a613-7e60-b3d7-61da207d3422" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e4c07-a613-7ef4-8c6d-e8a37172bc73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e4c07-a613-7a5c-ba70-41f0d6f96488" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITEDParenthetical" xlink:type="simple" xlink:href="cubi-20260630.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITEDParenthetical"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITEDParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e4c07-a613-7a68-9d98-0d7d461603c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e4c07-a613-7df3-933e-b5c13292daea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e4c07-a613-7a68-9d98-0d7d461603c8" xlink:to="loc_us-gaap_StatementTable_019e4c07-a613-7df3-933e-b5c13292daea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a613-7133-a3dd-b73080d86fd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e4c07-a613-7df3-933e-b5c13292daea" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a613-7133-a3dd-b73080d86fd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7133-a3dd-b73080d86fd3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a613-7133-a3dd-b73080d86fd3" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7133-a3dd-b73080d86fd3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7ed3-9f31-2903dad81f23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a613-7133-a3dd-b73080d86fd3" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7ed3-9f31-2903dad81f23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesEPreferredStockMember_019e4c07-a613-7fe8-abc1-e157cf88a818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesEPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7ed3-9f31-2903dad81f23" xlink:to="loc_us-gaap_SeriesEPreferredStockMember_019e4c07-a613-7fe8-abc1-e157cf88a818" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesFPreferredStockMember_019e4c07-a613-72a2-bd29-f2ad4ed8c59d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesFPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a613-7ed3-9f31-2903dad81f23" xlink:to="loc_us-gaap_SeriesFPreferredStockMember_019e4c07-a613-72a2-bd29-f2ad4ed8c59d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_019e4c07-a613-7579-9ad5-e51b1ae0c15e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e4c07-a613-7a68-9d98-0d7d461603c8" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_019e4c07-a613-7579-9ad5-e51b1ae0c15e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/EARNINGSLOSSPERSHAREAntiDilutiveSecuritiesExcludedfromComputationofEarningsLossPerShareDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#EARNINGSLOSSPERSHAREAntiDilutiveSecuritiesExcludedfromComputationofEarningsLossPerShareDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/EARNINGSLOSSPERSHAREAntiDilutiveSecuritiesExcludedfromComputationofEarningsLossPerShareDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e4c07-a613-7dbc-b779-98ad66df80b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e4c07-a613-7ae8-a209-c47e6cb34b1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e4c07-a613-7dbc-b779-98ad66df80b2" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e4c07-a613-7ae8-a209-c47e6cb34b1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e4c07-a613-7361-97ca-a2843ce446f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e4c07-a613-7ae8-a209-c47e6cb34b1a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e4c07-a613-7361-97ca-a2843ce446f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e4c07-a613-7361-97ca-a2843ce446f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e4c07-a613-7361-97ca-a2843ce446f8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e4c07-a613-7361-97ca-a2843ce446f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e4c07-a613-7c86-80a2-6add40678dde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e4c07-a613-7361-97ca-a2843ce446f8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e4c07-a613-7c86-80a2-6add40678dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019e4c07-a613-77ae-8739-cd61b38fc3a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e4c07-a613-7c86-80a2-6add40678dde" xlink:to="loc_us-gaap_StockCompensationPlanMember_019e4c07-a613-77ae-8739-cd61b38fc3a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e4c07-a613-77a8-8535-af38d49f228d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e4c07-a613-7dbc-b779-98ad66df80b2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e4c07-a613-77a8-8535-af38d49f228d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSBYCOMPONENTDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSBYCOMPONENTDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSBYCOMPONENTDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e4c07-a613-7cc1-b1fe-8032d61847dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e4c07-a613-7c3d-813d-cd9e09df8e53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e4c07-a613-7cc1-b1fe-8032d61847dd" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e4c07-a613-7c3d-813d-cd9e09df8e53" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-71ef-8f7b-1645af69c313" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e4c07-a613-7c3d-813d-cd9e09df8e53" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-71ef-8f7b-1645af69c313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e4c07-a613-71ef-8f7b-1645af69c313_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-71ef-8f7b-1645af69c313" xlink:to="loc_us-gaap_EquityComponentDomain_019e4c07-a613-71ef-8f7b-1645af69c313_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e4c07-a613-78cd-ac88-1574d93ccdad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e4c07-a613-71ef-8f7b-1645af69c313" xlink:to="loc_us-gaap_EquityComponentDomain_019e4c07-a613-78cd-ac88-1574d93ccdad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-751f-ad91-4fa8af55f2c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e4c07-a613-78cd-ac88-1574d93ccdad" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-751f-ad91-4fa8af55f2c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019e4c07-a613-7e99-9525-f88601f3ecb6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-751f-ad91-4fa8af55f2c0" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019e4c07-a613-7e99-9525-f88601f3ecb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e4c07-a613-7d01-8161-04f6ae549c83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e4c07-a613-751f-ad91-4fa8af55f2c0" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e4c07-a613-7d01-8161-04f6ae549c83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e4c07-a613-7cc1-b1fe-8032d61847dd" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e4c07-a613-7e06-864c-11ffde7f0c1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_StockholdersEquity_019e4c07-a613-7e06-864c-11ffde7f0c1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_019e4c07-a613-7741-a4f7-4e28ff66598a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_019e4c07-a613-7741-a4f7-4e28ff66598a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019e4c07-a613-7212-880f-af0452884963" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019e4c07-a613-7212-880f-af0452884963" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019e4c07-a613-7e41-9b23-6a2ea6087b6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019e4c07-a613-7e41-9b23-6a2ea6087b6d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e4c07-a613-7054-a0da-998ea6b93b44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e4c07-a613-7054-a0da-998ea6b93b44" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_019e4c07-a613-7c84-9f9d-b5d141cc4e39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_019e4c07-a613-7c84-9f9d-b5d141cc4e39" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019e4c07-a613-71c9-a795-638c89d4c95f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019e4c07-a613-71c9-a795-638c89d4c95f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossBeforeTax_019e4c07-a613-7a63-ade0-f9a473545ada" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossBeforeTax_019e4c07-a613-7a63-ade0-f9a473545ada" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax_019e4c07-a613-7aa0-9688-4dc522a980ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax_019e4c07-a613-7aa0-9688-4dc522a980ef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax_019e4c07-a613-716b-87f4-7bb148e6d897" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax_019e4c07-a613-716b-87f4-7bb148e6d897" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e4c07-a613-73a4-8ca5-2cdc985230a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e4c07-a613-7ded-8385-22eec051ea81" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e4c07-a613-73a4-8ca5-2cdc985230a1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e4c07-a613-7fdd-aeaf-ba6115bb2775" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7c37-91ba-9df4599b108c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7c37-91ba-9df4599b108c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-725d-a4a4-c62619292f95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7c37-91ba-9df4599b108c" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-725d-a4a4-c62619292f95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-725d-a4a4-c62619292f95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-725d-a4a4-c62619292f95" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-725d-a4a4-c62619292f95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-725d-a4a4-c62619292f95" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7347-8308-72dabdb49a07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7347-8308-72dabdb49a07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7714-b0ed-6de31f052cb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7714-b0ed-6de31f052cb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-76c4-842c-5d32daade61c" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-76c4-842c-5d32daade61c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-791a-9bbe-b27171952515" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-791a-9bbe-b27171952515" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-740a-b175-c2d4de097278" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-740a-b175-c2d4de097278" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7988-8987-ed7e69f00792" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-77e8-a7b9-3288430abdeb" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7988-8987-ed7e69f00792" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-712f-92ee-debfe0fe1297" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-712f-92ee-debfe0fe1297" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7cba-a02d-f67ddae84395" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7cba-a02d-f67ddae84395" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e4c07-a613-74f0-8004-39487be493f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e4c07-a613-74f0-8004-39487be493f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e4c07-a613-7ad7-ad6a-1563df609ae3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e4c07-a613-7ad7-ad6a-1563df609ae3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-7c39-9915-7af57c84d90b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-7c39-9915-7af57c84d90b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_019e4c07-a613-7107-8c6e-b29e86394b65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_019e4c07-a613-7107-8c6e-b29e86394b65" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InvestmentSecuritiesatFairValue_019e4c07-a613-7dcd-b325-53e348991cdb" xlink:href="cubi-20260630.xsd#cubi_InvestmentSecuritiesatFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_cubi_InvestmentSecuritiesatFairValue_019e4c07-a613-7dcd-b325-53e348991cdb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7297-a271-175f05707fe3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7297-a271-175f05707fe3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount_019e4c07-a613-76f5-813c-4afad29ebd1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-762e-914b-4366e37ad473" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount_019e4c07-a613-76f5-813c-4afad29ebd1e" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESAdditionalInformationDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7cb7-8da8-c05e10d7a6e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7cb7-8da8-c05e10d7a6e2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-73e2-8dd5-9a7aadf3df5d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7cb7-8da8-c05e10d7a6e2" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-73e2-8dd5-9a7aadf3df5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-73e2-8dd5-9a7aadf3df5d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-73e2-8dd5-9a7aadf3df5d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-73e2-8dd5-9a7aadf3df5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7acc-abbd-2bb60f66f552" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-73e2-8dd5-9a7aadf3df5d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7acc-abbd-2bb60f66f552" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-710a-b5d9-ddbd942bfd8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7acc-abbd-2bb60f66f552" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-710a-b5d9-ddbd942bfd8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7adb-ab66-d3c781382806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7acc-abbd-2bb60f66f552" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7adb-ab66-d3c781382806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7612-9d36-b95c8e40059e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7cb7-8da8-c05e10d7a6e2" xlink:to="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7612-9d36-b95c8e40059e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-7612-9d36-b95c8e40059e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7612-9d36-b95c8e40059e" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-7612-9d36-b95c8e40059e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-74f7-a83f-d8a3085037ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7612-9d36-b95c8e40059e" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-74f7-a83f-d8a3085037ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a613-7189-9499-88e3ba883229" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-74f7-a83f-d8a3085037ad" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a613-7189-9499-88e3ba883229" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-763c-9eca-bb8ae47918e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7cb7-8da8-c05e10d7a6e2" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-763c-9eca-bb8ae47918e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-763c-9eca-bb8ae47918e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-763c-9eca-bb8ae47918e4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-763c-9eca-bb8ae47918e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7925-84e8-e349190d90d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-763c-9eca-bb8ae47918e4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7925-84e8-e349190d90d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherInstallmentLoansMember_019e4c07-a613-7497-97f1-be4ca478d024" xlink:href="cubi-20260630.xsd#cubi_OtherInstallmentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7925-84e8-e349190d90d4" xlink:to="loc_cubi_OtherInstallmentLoansMember_019e4c07-a613-7497-97f1-be4ca478d024" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019e4c07-a613-7239-b30d-22b922dd8dfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019e4c07-a613-7239-b30d-22b922dd8dfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019e4c07-a613-7d68-81bd-dbb8cbb55b3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019e4c07-a613-7d68-81bd-dbb8cbb55b3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019e4c07-a613-783c-b50b-53e437c6a46a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019e4c07-a613-783c-b50b-53e437c6a46a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_019e4c07-a613-7300-a31e-9eacf42cc03d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_019e4c07-a613-7300-a31e-9eacf42cc03d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DebtInstrumentAvailableForSaleAccruedInterestReversal_019e4c07-a613-7d4e-8b10-f887250ca42d" xlink:href="cubi-20260630.xsd#cubi_DebtInstrumentAvailableForSaleAccruedInterestReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_cubi_DebtInstrumentAvailableForSaleAccruedInterestReversal_019e4c07-a613-7d4e-8b10-f887250ca42d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-79a6-83f8-431fc3b16cc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-79a6-83f8-431fc3b16cc1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecurities_019e4c07-a613-7e77-9c7b-af61408c1ec0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecurities_019e4c07-a613-7e77-9c7b-af61408c1ec0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7124-8265-07f6ad5787e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7124-8265-07f6ad5787e7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7163-8f36-24ae53612ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-705b-8543-bdfc2170d51f" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7163-8f36-24ae53612ca5" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAvailableforSaleDebtSecuritiesbyStatedMaturityDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESSummaryofAvailableforSaleDebtSecuritiesbyStatedMaturityDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAvailableforSaleDebtSecuritiesbyStatedMaturityDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-7e7c-8bae-5d5391cea735" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-758a-834d-bc986df88951" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-7e7c-8bae-5d5391cea735" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-758a-834d-bc986df88951" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-713b-aeca-4255b5bf9a6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-758a-834d-bc986df88951" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-713b-aeca-4255b5bf9a6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-713b-aeca-4255b5bf9a6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-713b-aeca-4255b5bf9a6b" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-713b-aeca-4255b5bf9a6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-713b-aeca-4255b5bf9a6b" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7c15-8e5c-b7603cda6bd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7c15-8e5c-b7603cda6bd5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7456-9432-27ea1191889a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7456-9432-27ea1191889a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-7a22-b10b-6a6d7c1350d8" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-7a22-b10b-6a6d7c1350d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7eab-9d1a-d4ba767de71f" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7eab-9d1a-d4ba767de71f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7274-b05c-c790d0ec63de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7de2-8089-3a57d46b7549" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7274-b05c-c790d0ec63de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-7e7c-8bae-5d5391cea735" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_019e4c07-a613-705e-a941-5adbf5b3de77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_019e4c07-a613-705e-a941-5adbf5b3de77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_019e4c07-a613-777e-9431-0f08f1170a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_019e4c07-a613-777e-9431-0f08f1170a6f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_019e4c07-a613-7328-9c0c-1a97ebfa1a61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_019e4c07-a613-7328-9c0c-1a97ebfa1a61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_019f8a8e-b19a-7099-8453-ce9dfa599e70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_019f8a8e-b19a-7099-8453-ce9dfa599e70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_019e4c07-a613-72dd-ab86-c32a80c16b96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_019e4c07-a613-72dd-ab86-c32a80c16b96" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7aab-81c8-e679ff53628b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_019f7097-6544-7a24-9f0d-fd46f5eddffb" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7aab-81c8-e679ff53628b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-7e7c-8bae-5d5391cea735" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_019e4c07-a613-718f-ab85-1729766da86c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_019e4c07-a613-718f-ab85-1729766da86c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_019e4c07-a613-789f-80c0-b5fb246e099a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_019e4c07-a613-789f-80c0-b5fb246e099a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_019e4c07-a613-7193-992d-edd18b84e54d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_019e4c07-a613-7193-992d-edd18b84e54d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_019f8a8e-797f-732e-ade5-83e8e3b961bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_019f8a8e-797f-732e-ade5-83e8e3b961bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019e4c07-a613-777d-9557-d07145a69a62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019e4c07-a613-777d-9557-d07145a69a62" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-7ca0-a7e8-df8f43ea33e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_019f7097-cb95-7a42-8c1e-69acf7c3d7c7" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a613-7ca0-a7e8-df8f43ea33e7" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESGrossUnrealizedLossesandFairValueAggregatedbyInvestmentCategoryDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESGrossUnrealizedLossesandFairValueAggregatedbyInvestmentCategoryDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESGrossUnrealizedLossesandFairValueAggregatedbyInvestmentCategoryDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7953-9e5a-fc5ae2ecdee8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7953-9e5a-fc5ae2ecdee8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7e0a-99eb-c17ad6c8c35f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e4c07-a613-7953-9e5a-fc5ae2ecdee8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7e0a-99eb-c17ad6c8c35f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7e0a-99eb-c17ad6c8c35f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7e0a-99eb-c17ad6c8c35f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7e0a-99eb-c17ad6c8c35f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7e0a-99eb-c17ad6c8c35f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7982-abfc-69062af7e452" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7982-abfc-69062af7e452" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7a53-a2f4-91a244b4d80d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7a53-a2f4-91a244b4d80d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-73d6-a879-789ab1087851" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-73d6-a879-789ab1087851" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7752-b241-dcfd869677eb" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7752-b241-dcfd869677eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-758e-9e36-3182be7e9943" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-758e-9e36-3182be7e9943" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7275-8e0e-7e51065ec670" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-718c-b948-5e0fb5050e8a" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-7275-8e0e-7e51065ec670" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019e4c07-a613-772e-afe2-c8d04cea9da5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019e4c07-a613-772e-afe2-c8d04cea9da5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019e4c07-a613-7602-80ad-a5368cf4c54f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019e4c07-a613-7602-80ad-a5368cf4c54f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019e4c07-a613-7751-b6e0-76fffe0eae08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019e4c07-a613-7751-b6e0-76fffe0eae08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019e4c07-a613-72f6-8357-1ccb58d43b05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019e4c07-a613-72f6-8357-1ccb58d43b05" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019e4c07-a613-73ba-ba45-fb50e728ab30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019e4c07-a613-73ba-ba45-fb50e728ab30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_019e4c07-a613-7f49-b5b0-ff4337a33ae2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e4c07-a613-78f2-9af9-56bbbf339d34" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_019e4c07-a613-7f49-b5b0-ff4337a33ae2" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESCreditValuationAllowanceforAvailableforSaleDebtSecuritiesDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESCreditValuationAllowanceforAvailableforSaleDebtSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESCreditValuationAllowanceforAvailableforSaleDebtSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems_019e4c07-a613-706f-b301-bb80d074ecca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable_019e4c07-a613-7932-acc2-850526eb4394" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems_019e4c07-a613-706f-b301-bb80d074ecca" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable_019e4c07-a613-7932-acc2-850526eb4394" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7137-a51f-62d073618e3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable_019e4c07-a613-7932-acc2-850526eb4394" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7137-a51f-62d073618e3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7137-a51f-62d073618e3d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7137-a51f-62d073618e3d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7137-a51f-62d073618e3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7558-96b3-ac78393ed375" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7137-a51f-62d073618e3d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7558-96b3-ac78393ed375" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7005-9129-ee3c64d52795" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7558-96b3-ac78393ed375" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-7005-9129-ee3c64d52795" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-7dc5-bd82-aea75a21b692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7558-96b3-ac78393ed375" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a613-7dc5-bd82-aea75a21b692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PrivateLabelContractManufacturingOrganizationCMOMember_019e4c07-a613-7085-b9dd-2396cc599abc" xlink:href="cubi-20260630.xsd#cubi_PrivateLabelContractManufacturingOrganizationCMOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7558-96b3-ac78393ed375" xlink:to="loc_cubi_PrivateLabelContractManufacturingOrganizationCMOMember_019e4c07-a613-7085-b9dd-2396cc599abc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems_019e4c07-a613-706f-b301-bb80d074ecca" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-731b-97cd-564ab5d362cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-731b-97cd-564ab5d362cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded_019ed1c2-6110-7076-99e7-cfd8375f0fad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded_019ed1c2-6110-7076-99e7-cfd8375f0fad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal_019e4c07-a613-7974-b956-f9420f4f55f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal_019e4c07-a613-7974-b956-f9420f4f55f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossDecreaseOnPreviouslyImpairedSecurities_019e4c07-a613-789a-b42b-70bc4f7d1c79" xlink:href="cubi-20260630.xsd#cubi_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossDecreaseOnPreviouslyImpairedSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_cubi_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossDecreaseOnPreviouslyImpairedSecurities_019e4c07-a613-789a-b42b-70bc4f7d1c79" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold_019e4c07-a613-70f6-b12c-ade7831d4431" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold_019e4c07-a613-70f6-b12c-ade7831d4431" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease_019ed110-60ac-7e8f-bfba-68af4bec945b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward_019e4c07-a613-7074-8b40-efbe9a91d131" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease_019ed110-60ac-7e8f-bfba-68af4bec945b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7665-8730-c15c3f17a02a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail_1" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail_1"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofAmortizedCostandApproximateFairValueofInvestmentSecuritiesDetail_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7687-af26-a491d5796354" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7687-af26-a491d5796354" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7077-aecd-05bfacbdeb69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7687-af26-a491d5796354" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7077-aecd-05bfacbdeb69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7077-aecd-05bfacbdeb69_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7077-aecd-05bfacbdeb69" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7077-aecd-05bfacbdeb69_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7077-aecd-05bfacbdeb69" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-748c-8fbd-b9318b215590" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-748c-8fbd-b9318b215590" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-76ca-8d8a-86bd00995bde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-76ca-8d8a-86bd00995bde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-79f1-a852-4de5192f346c" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-79f1-a852-4de5192f346c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-77a2-ae60-5226b7954d8f" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-77a2-ae60-5226b7954d8f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-74ab-b960-b124dbbfd391" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-74ab-b960-b124dbbfd391" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-73b2-b4fd-387607754cbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7c7c-8e19-0b275e104fd2" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-73b2-b4fd-387607754cbb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7dbc-b825-453457acc16c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7dbc-b825-453457acc16c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-77bb-bbdb-8a0c43a9fe6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-77bb-bbdb-8a0c43a9fe6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7306-a34c-4c8772787af4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7306-a34c-4c8772787af4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_019e4c07-a613-7967-bf80-588672168aaf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_019e4c07-a613-7967-bf80-588672168aaf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_019e4c07-a613-7383-af98-0e43a954d960" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_019e4c07-a613-7383-af98-0e43a954d960" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019e4c07-a613-71cd-bb8a-7fe392fd8715" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019e4c07-a613-71cd-bb8a-7fe392fd8715" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7a99-85ab-2d4c42550311" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7fbd-88db-1731a55f1226" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7a99-85ab-2d4c42550311" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofHeldtoMaturityDebtSecuritiesbyStatedMaturityDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESSummaryofHeldtoMaturityDebtSecuritiesbyStatedMaturityDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESSummaryofHeldtoMaturityDebtSecuritiesbyStatedMaturityDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7c59-b671-c4a92ceb06fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7965-8463-f23af3ade8ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7c59-b671-c4a92ceb06fd" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7965-8463-f23af3ade8ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-7965-8463-f23af3ade8ea" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7331-bd4d-1c0f7d5ac5d4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-71f8-ae28-1500541e049e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-71f8-ae28-1500541e049e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7caf-82d3-b73c04637d1c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7caf-82d3-b73c04637d1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-77ba-a3fe-7ab50e2be195" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-77ba-a3fe-7ab50e2be195" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-7eb3-90c7-e188fbde1541" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-7eb3-90c7-e188fbde1541" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7da3-97fe-e26ad43f426e" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7da3-97fe-e26ad43f426e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-764d-8495-6fd93adae237" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-780e-8ba1-cfa49d670e61" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-764d-8495-6fd93adae237" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate_019e4c07-a613-7694-a1c9-d5a9ae5bf5a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7c59-b671-c4a92ceb06fd" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate_019e4c07-a613-7694-a1c9-d5a9ae5bf5a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019e4c07-a613-7a57-a205-175a14ca4af9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-7c59-b671-c4a92ceb06fd" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019e4c07-a613-7a57-a205-175a14ca4af9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/INVESTMENTSECURITIESDebtSecuritiesHeldtoMaturityCreditQualityIndicatorDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#INVESTMENTSECURITIESDebtSecuritiesHeldtoMaturityCreditQualityIndicatorDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/INVESTMENTSECURITIESDebtSecuritiesHeldtoMaturityCreditQualityIndicatorDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-75ed-ada7-26c18c49dc85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-70ab-857f-b8885081bf07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-75ed-ada7-26c18c49dc85" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-70ab-857f-b8885081bf07" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CreditRatingAxis_019e4c07-a613-7741-84b4-46794dd26fd8" xlink:href="cubi-20260630.xsd#cubi_CreditRatingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-70ab-857f-b8885081bf07" xlink:to="loc_cubi_CreditRatingAxis_019e4c07-a613-7741-84b4-46794dd26fd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CreditRatingDomain_019e4c07-a613-7741-84b4-46794dd26fd8_default" xlink:href="cubi-20260630.xsd#cubi_CreditRatingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cubi_CreditRatingAxis_019e4c07-a613-7741-84b4-46794dd26fd8" xlink:to="loc_cubi_CreditRatingDomain_019e4c07-a613-7741-84b4-46794dd26fd8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CreditRatingDomain_019e4c07-a613-7816-a321-47ec71ab9773" xlink:href="cubi-20260630.xsd#cubi_CreditRatingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cubi_CreditRatingAxis_019e4c07-a613-7741-84b4-46794dd26fd8" xlink:to="loc_cubi_CreditRatingDomain_019e4c07-a613-7816-a321-47ec71ab9773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CreditRatingAAARatingMember_019e4c07-a613-780b-b15d-1be7ac4f2583" xlink:href="cubi-20260630.xsd#cubi_CreditRatingAAARatingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CreditRatingDomain_019e4c07-a613-7816-a321-47ec71ab9773" xlink:to="loc_cubi_CreditRatingAAARatingMember_019e4c07-a613-780b-b15d-1be7ac4f2583" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_NotRatedMember_019e4c07-a613-7d05-8b5e-fda86a7d0975" xlink:href="cubi-20260630.xsd#cubi_NotRatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CreditRatingDomain_019e4c07-a613-7816-a321-47ec71ab9773" xlink:to="loc_cubi_NotRatedMember_019e4c07-a613-7d05-8b5e-fda86a7d0975" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7678-b908-fa3a1eb9cb31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_019e4c07-a613-70ab-857f-b8885081bf07" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7678-b908-fa3a1eb9cb31" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7678-b908-fa3a1eb9cb31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7678-b908-fa3a1eb9cb31" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-7678-b908-fa3a1eb9cb31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a613-7678-b908-fa3a1eb9cb31" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-787d-b03e-38d7214b8432" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a613-787d-b03e-38d7214b8432" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7500-b588-b10090b5acc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a613-7500-b588-b10090b5acc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-71b3-b302-3b5778c23554" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_cubi_AgencyGuaranteedCommercialMortgageBackedSecuritiesMember_019e4c07-a613-71b3-b302-3b5778c23554" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-71fc-bd9b-672cf79fa912" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a613-71fc-bd9b-672cf79fa912" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7e1a-b7f2-dfc346946d23" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a613-7e1a-b7f2-dfc346946d23" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-77b5-871e-1d83452e01db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a613-719c-8f7d-bbfe92cddd09" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a613-77b5-871e-1d83452e01db" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-78ef-9f49-79f2c6cc8e33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_019e4c07-a613-75ed-ada7-26c18c49dc85" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-78ef-9f49-79f2c6cc8e33" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoansandLeasesReceivableDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoansandLeasesReceivableDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoansandLeasesReceivableDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-702d-b24e-8aae687c9c79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-702d-b24e-8aae687c9c79" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a613-742f-a635-12a677f8ca8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-702d-b24e-8aae687c9c79" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a613-742f-a635-12a677f8ca8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-742f-a635-12a677f8ca8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a613-742f-a635-12a677f8ca8a" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-742f-a635-12a677f8ca8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-7867-b3d3-6149a7324130" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a613-742f-a635-12a677f8ca8a" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-7867-b3d3-6149a7324130" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialBorrowerMember_019e4c07-a613-71e4-ae47-e2b80c63292d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialBorrowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-7867-b3d3-6149a7324130" xlink:to="loc_us-gaap_CommercialBorrowerMember_019e4c07-a613-71e4-ae47-e2b80c63292d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerBorrowerMember_019e4c07-a613-7455-9018-302e531dcaf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConsumerBorrowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a613-7867-b3d3-6149a7324130" xlink:to="loc_us-gaap_ConsumerBorrowerMember_019e4c07-a613-7455-9018-302e531dcaf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7e94-8351-0b99e3513b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-702d-b24e-8aae687c9c79" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7e94-8351-0b99e3513b0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7e94-8351-0b99e3513b0a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7e94-8351-0b99e3513b0a" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7e94-8351-0b99e3513b0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7e94-8351-0b99e3513b0a" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_SpecialtyLendingMember_019e4c07-a613-7ac3-a907-9da0060e60df" xlink:href="cubi-20260630.xsd#cubi_SpecialtyLendingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_SpecialtyLendingMember_019e4c07-a613-7ac3-a907-9da0060e60df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherCommercialAndIndustrialMember_019e4c07-a613-704e-9fbb-b1e704bdad10" xlink:href="cubi-20260630.xsd#cubi_OtherCommercialAndIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_OtherCommercialAndIndustrialMember_019e4c07-a613-704e-9fbb-b1e704bdad10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a613-7aba-b338-967e32e28a41" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a613-7aba-b338-967e32e28a41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedMember_019e4c07-a613-7746-9125-35c942bc5e7e" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedMember_019e4c07-a613-7746-9125-35c942bc5e7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_019e4c07-a613-755f-affd-c354facb1525" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_019e4c07-a613-755f-affd-c354facb1525" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a613-72d0-94f1-4bcefa42f0a1" xlink:href="cubi-20260630.xsd#cubi_ConstructionPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a613-72d0-94f1-4bcefa42f0a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a613-7aec-8d68-7bdfa8c9df4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a613-7aec-8d68-7bdfa8c9df4e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a613-7499-bf02-876aba79b763" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a613-7499-bf02-876aba79b763" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a613-7573-ad87-4051633abcb6" xlink:href="cubi-20260630.xsd#cubi_PersonalInstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a613-7573-ad87-4051633abcb6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherInstallmentLoansPortfolioSegmentMember_019e4c07-a613-7985-8abd-bd3749243ec0" xlink:href="cubi-20260630.xsd#cubi_OtherInstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_cubi_OtherInstallmentLoansPortfolioSegmentMember_019e4c07-a613-7985-8abd-bd3749243ec0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_019e4c07-a613-78fc-8359-9bf902a2a918" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeasesPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f90-93ec-9ab7084a1ed0" xlink:to="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_019e4c07-a613-78fc-8359-9bf902a2a918" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7972-b93a-35c7f62f1d28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-7972-b93a-35c7f62f1d28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLos_019e4c07-a613-7a32-808f-e54b615395bf" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLos"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLos_019e4c07-a613-7a32-808f-e54b615395bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableMortgageWarehouse_019e4c07-a613-76e9-b8d0-c3f97d953f1f" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableMortgageWarehouse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableMortgageWarehouse_019e4c07-a613-76e9-b8d0-c3f97d953f1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableInstallment_019e4c07-a613-7738-9445-a7c7aba3e500" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableInstallment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_cubi_FinancingReceivableExcludingAccruedInterestLoansReceivableInstallment_019e4c07-a613-7738-9445-a7c7aba3e500" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-74f7-bb82-ffb2d62fa9f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-74f7-bb82-ffb2d62fa9f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7716-b619-9ce46af50ee2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7716-b619-9ce46af50ee2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLoss_019e4c07-a613-7629-b50f-f14bbd640b5b" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_cubi_FinancingReceivableExcludingAccruedInterestIncludingPaycheckProtectionProgramReceivablesBeforeAllowanceForCreditLoss_019e4c07-a613-7629-b50f-f14bbd640b5b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount_019e4c07-a613-7be6-a582-86cfd40168fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a613-7f7c-a80a-fa36e49f5329" xlink:to="loc_us-gaap_FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount_019e4c07-a613-7be6-a582-86cfd40168fe" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESAdditionalInformationDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableModificationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralAxis_019e4c07-a613-7b37-b9df-25ad7c9da4d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:to="loc_us-gaap_CollateralAxis_019e4c07-a613-7b37-b9df-25ad7c9da4d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralDomain_019e4c07-a613-7b37-b9df-25ad7c9da4d0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CollateralAxis_019e4c07-a613-7b37-b9df-25ad7c9da4d0" xlink:to="loc_us-gaap_CollateralDomain_019e4c07-a613-7b37-b9df-25ad7c9da4d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralDomain_019e4c07-a613-7fd0-83cf-70e58435c55e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CollateralAxis_019e4c07-a613-7b37-b9df-25ad7c9da4d0" xlink:to="loc_us-gaap_CollateralDomain_019e4c07-a613-7fd0-83cf-70e58435c55e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_019e4c07-a613-779c-8289-385f33dbb47f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollateralDomain_019e4c07-a613-7fd0-83cf-70e58435c55e" xlink:to="loc_us-gaap_CommercialRealEstateMember_019e4c07-a613-779c-8289-385f33dbb47f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7f95-837c-16fe11854de4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7f95-837c-16fe11854de4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f95-837c-16fe11854de4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7f95-837c-16fe11854de4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7f95-837c-16fe11854de4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7bcb-b72c-5ad913113e66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7f95-837c-16fe11854de4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7bcb-b72c-5ad913113e66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialandIndustrialMember_019e4c07-a613-741a-b396-f09681040b46" xlink:href="cubi-20260630.xsd#cubi_CommercialandIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7bcb-b72c-5ad913113e66" xlink:to="loc_cubi_CommercialandIndustrialMember_019e4c07-a613-741a-b396-f09681040b46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_019e4c07-a613-7634-b49c-631104100aa3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_019e4c07-a613-7634-b49c-631104100aa3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-7634-b49c-631104100aa3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_019e4c07-a613-7634-b49c-631104100aa3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-7634-b49c-631104100aa3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-745e-bca3-82bafd392526" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_019e4c07-a613-7634-b49c-631104100aa3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-745e-bca3-82bafd392526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CollateralDependentLoanMember_019e4c07-a613-782e-89de-dd9bee85b352" xlink:href="cubi-20260630.xsd#cubi_CollateralDependentLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-745e-bca3-82bafd392526" xlink:to="loc_cubi_CollateralDependentLoanMember_019e4c07-a613-782e-89de-dd9bee85b352" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConsumerInstallmentLoansMember_019e4c07-a613-7c84-b1e1-00ed2dd160f2" xlink:href="cubi-20260630.xsd#cubi_ConsumerInstallmentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_019e4c07-a613-745e-bca3-82bafd392526" xlink:to="loc_cubi_ConsumerInstallmentLoansMember_019e4c07-a613-7c84-b1e1-00ed2dd160f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7ff8-b62c-329a2f4c5356" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a613-7321-8b1b-e12c1ebd42f7" xlink:to="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7ff8-b62c-329a2f4c5356" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-7ff8-b62c-329a2f4c5356_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7ff8-b62c-329a2f4c5356" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-7ff8-b62c-329a2f4c5356_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-778d-b14a-4c545435579f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a613-7ff8-b62c-329a2f4c5356" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-778d-b14a-4c545435579f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a613-7cf7-a570-280ce28768e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_019e4c07-a613-778d-b14a-4c545435579f" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a613-7cf7-a570-280ce28768e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7c64-8dc8-a4e5e5513839" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7c64-8dc8-a4e5e5513839" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7e1a-84db-1fbb2138352b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a613-7e1a-84db-1fbb2138352b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_LoansHeldForSaleAverageLifeFromPurchaseToSale_019e4c07-a613-78f7-b731-ee19c86e086a" xlink:href="cubi-20260630.xsd#cubi_LoansHeldForSaleAverageLifeFromPurchaseToSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_cubi_LoansHeldForSaleAverageLifeFromPurchaseToSale_019e4c07-a613-78f7-b731-ee19c86e086a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus_019e4c07-a613-7c26-8ff4-670a4038c371" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus_019e4c07-a613-7c26-8ff4-670a4038c371" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7bee-b65e-c125ff27cf84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a613-7bee-b65e-c125ff27cf84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease_019e4c07-a613-7c1e-8086-ce9a77c5f37b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease_019e4c07-a613-7c1e-8086-ce9a77c5f37b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend_019e4c07-a613-721e-ba75-957ccf2cc952" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend_019e4c07-a613-721e-ba75-957ccf2cc952" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-74b9-a354-00f232528344" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a613-743c-a8c7-ffb782fd4b57" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a613-74b9-a354-00f232528344" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESPerformanceStatusDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESPerformanceStatusDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESPerformanceStatusDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d1-7590-a0a7-3889fab4d89d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-749e-b87e-cb791dc23794" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d1-7590-a0a7-3889fab4d89d" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-749e-b87e-cb791dc23794" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7b1c-8c31-d9ad13dd7c39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-749e-b87e-cb791dc23794" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7b1c-8c31-d9ad13dd7c39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7b1c-8c31-d9ad13dd7c39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7b1c-8c31-d9ad13dd7c39" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7b1c-8c31-d9ad13dd7c39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a613-7b1c-8c31-d9ad13dd7c39" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a613-713c-91cf-e6ef8a9e81fe" xlink:href="cubi-20260630.xsd#cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a613-713c-91cf-e6ef8a9e81fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a613-783a-b2d8-0e4ca21fd4cb" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a613-783a-b2d8-0e4ca21fd4cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a613-75c8-98fe-b68742d1a5b5" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a613-75c8-98fe-b68742d1a5b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a613-77bc-9104-99b0b39069e2" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a613-77bc-9104-99b0b39069e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a613-7860-928c-7e2040a3020c" xlink:href="cubi-20260630.xsd#cubi_ConstructionPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a613-7860-928c-7e2040a3020c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a613-7c80-b263-aa9ade628671" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a613-7c80-b263-aa9ade628671" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a613-7b33-be13-82bb0ecc39f8" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a613-7b33-be13-82bb0ecc39f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7aeb-9397-8a911af60b09" xlink:href="cubi-20260630.xsd#cubi_InstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a613-7d2a-9e63-80f83a00439d" xlink:to="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7aeb-9397-8a911af60b09" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-785d-85a4-fdb04a35d88f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a613-749e-b87e-cb791dc23794" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-785d-85a4-fdb04a35d88f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-785d-85a4-fdb04a35d88f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-785d-85a4-fdb04a35d88f" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-785d-85a4-fdb04a35d88f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7009-b160-44ea11142b04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-785d-85a4-fdb04a35d88f" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7009-b160-44ea11142b04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetPastDueMember_019e4c07-a6d1-7db4-99d5-5e6cc4dda63a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialAssetPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7009-b160-44ea11142b04" xlink:to="loc_us-gaap_FinancialAssetPastDueMember_019e4c07-a6d1-7db4-99d5-5e6cc4dda63a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_019e4c07-a6d1-7b3f-8942-9606fc041846" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivables30To59DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialAssetPastDueMember_019e4c07-a6d1-7db4-99d5-5e6cc4dda63a" xlink:to="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_019e4c07-a6d1-7b3f-8942-9606fc041846" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_019e4c07-a6d1-73d4-9c4e-75ac2e23b1c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivables60To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialAssetPastDueMember_019e4c07-a6d1-7db4-99d5-5e6cc4dda63a" xlink:to="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_019e4c07-a6d1-73d4-9c4e-75ac2e23b1c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_019e4c07-a6d1-75df-aa45-d4ebef862fbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialAssetPastDueMember_019e4c07-a6d1-7db4-99d5-5e6cc4dda63a" xlink:to="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_019e4c07-a6d1-75df-aa45-d4ebef862fbc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetNotPastDueMember_019e4c07-a6d1-76a3-8586-52afca146ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialAssetNotPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7009-b160-44ea11142b04" xlink:to="loc_us-gaap_FinancialAssetNotPastDueMember_019e4c07-a6d1-76a3-8586-52afca146ec3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d1-7429-a3fe-8bf9d42cf517" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d1-7590-a0a7-3889fab4d89d" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d1-7429-a3fe-8bf9d42cf517" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_019e4c07-a6d1-77af-a70b-10bc90a69c90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d1-7590-a0a7-3889fab4d89d" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_019e4c07-a6d1-77af-a70b-10bc90a69c90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice_019e4c07-a6d1-7551-9d16-f7959ea0fa91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d1-7590-a0a7-3889fab4d89d" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice_019e4c07-a6d1-7551-9d16-f7959ea0fa91" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESSummaryofAmortizedCostofLoansandLeasesonNonaccrualStatusDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESSummaryofAmortizedCostofLoansandLeasesonNonaccrualStatusDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESSummaryofAmortizedCostofLoansandLeasesonNonaccrualStatusDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableImpairedLineItems_019e4c07-a6d1-7c7b-b1e2-a0fa2c617491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableImpairedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfImpairedFinancingReceivableTable_019e4c07-a6d1-7ef6-994f-e91bb0df9c49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfImpairedFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableImpairedLineItems_019e4c07-a6d1-7c7b-b1e2-a0fa2c617491" xlink:to="loc_us-gaap_ScheduleOfImpairedFinancingReceivableTable_019e4c07-a6d1-7ef6-994f-e91bb0df9c49" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-70ee-a3e7-5e40358ea375" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfImpairedFinancingReceivableTable_019e4c07-a6d1-7ef6-994f-e91bb0df9c49" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-70ee-a3e7-5e40358ea375" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-70ee-a3e7-5e40358ea375_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-70ee-a3e7-5e40358ea375" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-70ee-a3e7-5e40358ea375_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-70ee-a3e7-5e40358ea375" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-70a9-9f4e-e6ee5cedc9fb" xlink:href="cubi-20260630.xsd#cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-70a9-9f4e-e6ee5cedc9fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-76da-9a2f-bb5d1b574538" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-76da-9a2f-bb5d1b574538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-703a-810e-4d479685283a" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-703a-810e-4d479685283a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7bc2-a930-786843b81aad" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7bc2-a930-786843b81aad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7f47-8d2f-fa1dbdbf3f71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7f47-8d2f-fa1dbdbf3f71" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d1-784f-a911-3867766a9c9a" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d1-784f-a911-3867766a9c9a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7ec1-95f2-d1a2951a7f96" xlink:href="cubi-20260630.xsd#cubi_InstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7901-89f1-5dce86147692" xlink:to="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7ec1-95f2-d1a2951a7f96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_019e4c07-a6d1-7939-9992-b8956e8d84bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableImpairedLineItems_019e4c07-a6d1-7c7b-b1e2-a0fa2c617491" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_019e4c07-a6d1-7939-9992-b8956e8d84bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableNonaccrualWithAllowance_019e4c07-a6d1-771e-b287-88ee4587c971" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableNonaccrualWithAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableImpairedLineItems_019e4c07-a6d1-7c7b-b1e2-a0fa2c617491" xlink:to="loc_cubi_FinancingReceivableNonaccrualWithAllowance_019e4c07-a6d1-771e-b287-88ee4587c971" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_019e4c07-a6d1-7183-bc32-813d7bb9f483" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableImpairedLineItems_019e4c07-a6d1-7c7b-b1e2-a0fa2c617491" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_019e4c07-a6d1-7183-bc32-813d7bb9f483" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofAllowanceforCreditLossesDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofAllowanceforCreditLossesDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofAllowanceforCreditLossesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_019e4c07-a6d1-7166-8f73-65e7743e9f6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_019e4c07-a6d1-7f59-b0d5-3b10f842de46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_019e4c07-a6d1-7166-8f73-65e7743e9f6f" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_019e4c07-a6d1-7f59-b0d5-3b10f842de46" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-726a-87db-1c3d7891aaa8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_019e4c07-a6d1-7f59-b0d5-3b10f842de46" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-726a-87db-1c3d7891aaa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-726a-87db-1c3d7891aaa8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-726a-87db-1c3d7891aaa8" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-726a-87db-1c3d7891aaa8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-726a-87db-1c3d7891aaa8" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-748e-bafe-ff6751693300" xlink:href="cubi-20260630.xsd#cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-748e-bafe-ff6751693300" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-7960-81f7-8c0184518f94" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-7960-81f7-8c0184518f94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ec3-93f4-84b30cb9c7c3" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ec3-93f4-84b30cb9c7c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ce6-9529-697bea245ead" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ce6-9529-697bea245ead" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a6d1-7a58-a299-312dd338492a" xlink:href="cubi-20260630.xsd#cubi_ConstructionPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a6d1-7a58-a299-312dd338492a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-70a8-bf89-5cf6101a1cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-70a8-bf89-5cf6101a1cc7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d1-78fd-ad4c-42aaf4adfd07" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d1-78fd-ad4c-42aaf4adfd07" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7b59-84f8-3545ef309a7b" xlink:href="cubi-20260630.xsd#cubi_InstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7446-9eee-5be87890b68d" xlink:to="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7b59-84f8-3545ef309a7b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_019e4c07-a6d1-7166-8f73-65e7743e9f6f" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a6d1-7873-9acf-18e1899942cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a6d1-7873-9acf-18e1899942cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease_019ed1b9-8795-75c1-b861-a342368e1f35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease_019ed1b9-8795-75c1-b861-a342368e1f35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_019e4c07-a6d1-7470-ac78-1947f244517b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_019e4c07-a6d1-7470-ac78-1947f244517b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_019e4c07-a6d1-748c-bd7e-0f6c83d915aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_019e4c07-a6d1-748c-bd7e-0f6c83d915aa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_019e4c07-a6d1-7c21-b81b-9067d3ac0e08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_019e4c07-a6d1-7442-9edf-6a1edc6efdb0" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_019e4c07-a6d1-7c21-b81b-9067d3ac0e08" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_019e4c07-a6d1-79cb-945e-dfd9ad1e7044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_019ed1c0-6922-7c48-b304-9aad954ae4c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_019e4c07-a6d1-7166-8f73-65e7743e9f6f" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_019ed1c0-6922-7c48-b304-9aad954ae4c9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESLoanModificationsforBorrowersExperiencingFinancialDifficultyDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESLoanModificationsforBorrowersExperiencingFinancialDifficultyDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESLoanModificationsforBorrowersExperiencingFinancialDifficultyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableModificationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a6d1-7551-bee2-66263ff1234f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a6d1-7551-bee2-66263ff1234f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-701c-8c11-3d0147fb9b96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a6d1-7551-bee2-66263ff1234f" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-701c-8c11-3d0147fb9b96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-701c-8c11-3d0147fb9b96_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-701c-8c11-3d0147fb9b96" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-701c-8c11-3d0147fb9b96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-701c-8c11-3d0147fb9b96" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialAndIndustrialIncludingSpecializedLendingMember_019e4c07-a6d1-714c-8873-b0339b84a9dc" xlink:href="cubi-20260630.xsd#cubi_CommercialAndIndustrialIncludingSpecializedLendingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_cubi_CommercialAndIndustrialIncludingSpecializedLendingMember_019e4c07-a6d1-714c-8873-b0339b84a9dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-742d-b82d-155aa0e4e610" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-742d-b82d-155aa0e4e610" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-76d4-b5b9-a47975334f05" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-76d4-b5b9-a47975334f05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7209-b9d7-184ebcd72398" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7209-b9d7-184ebcd72398" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingMember_019e4c07-a6d1-7eb2-9af7-3dcc3dbd8a10" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_cubi_ManufacturedHousingMember_019e4c07-a6d1-7eb2-9af7-3dcc3dbd8a10" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7dde-863e-292f44a9b212" xlink:href="cubi-20260630.xsd#cubi_PersonalInstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7d77-b53c-bf69caf3a683" xlink:to="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a6d1-7dde-863e-292f44a9b212" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationAxis_019e4c07-a6d1-7439-9679-8631e5241129" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoanRestructuringModificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a6d1-7551-bee2-66263ff1234f" xlink:to="loc_us-gaap_LoanRestructuringModificationAxis_019e4c07-a6d1-7439-9679-8631e5241129" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7439-9679-8631e5241129_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_019e4c07-a6d1-7439-9679-8631e5241129" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7439-9679-8631e5241129_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_019e4c07-a6d1-7439-9679-8631e5241129" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualInterestRateReductionMember_019e4c07-a6d1-78ab-9ce9-360018c4d3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractualInterestRateReductionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:to="loc_us-gaap_ContractualInterestRateReductionMember_019e4c07-a6d1-78ab-9ce9-360018c4d3ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtendedMaturityMember_019e4c07-a6d1-7a6c-b6b1-4e961483293e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ExtendedMaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:to="loc_us-gaap_ExtendedMaturityMember_019e4c07-a6d1-7a6c-b6b1-4e961483293e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentDeferralMember_019e4c07-a6d1-7b9e-bb53-b7e0a9e5b809" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:to="loc_us-gaap_PaymentDeferralMember_019e4c07-a6d1-7b9e-bb53-b7e0a9e5b809" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrincipalForgivenessMember_019e4c07-a6d1-780a-976e-274d6933c59e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrincipalForgivenessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:to="loc_us-gaap_PrincipalForgivenessMember_019e4c07-a6d1-780a-976e-274d6933c59e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateReductionAndTermExtensionMember_019e4c07-a6d1-73c2-9ecf-55c88d6257b0" xlink:href="cubi-20260630.xsd#cubi_InterestRateReductionAndTermExtensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_019e4c07-a6d1-7970-82b2-97b872cdf5c4" xlink:to="loc_cubi_InterestRateReductionAndTermExtensionMember_019e4c07-a6d1-73c2-9ecf-55c88d6257b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_019e4c07-a6d1-7551-bee2-66263ff1234f" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_019e4c07-a6d1-7bd1-ae31-0a27d0f8077a" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_019e4c07-a6d1-7d28-9218-0a11c371ceb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivables30To59DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:to="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_019e4c07-a6d1-7d28-9218-0a11c371ceb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_019e4c07-a6d1-7419-8fc4-097552d43b97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivables60To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:to="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_019e4c07-a6d1-7419-8fc4-097552d43b97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_019e4c07-a6d1-740f-8404-e56c2f66f180" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:to="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_019e4c07-a6d1-740f-8404-e56c2f66f180" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetNotPastDueMember_019e4c07-a6d1-769e-aa18-bdaa692b2244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialAssetNotPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_019e4c07-a6d1-79cb-b931-e669cdedf6bc" xlink:to="loc_us-gaap_FinancialAssetNotPastDueMember_019e4c07-a6d1-769e-aa18-bdaa692b2244" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod_019e4c07-a6d1-7be8-84bb-13cbf054a41c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod_019e4c07-a6d1-7be8-84bb-13cbf054a41c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent_019e4c07-a6d1-753e-a84b-156b791f60c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent_019e4c07-a6d1-753e-a84b-156b791f60c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableModifiedWeightAverageInterestRateDecreaseFromModification_019e4c07-a6d1-7a5f-bb27-c139fbb3b1e6" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableModifiedWeightAverageInterestRateDecreaseFromModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_cubi_FinancingReceivableModifiedWeightAverageInterestRateDecreaseFromModification_019e4c07-a6d1-7a5f-bb27-c139fbb3b1e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification_019e4c07-a6d1-75aa-b670-94f4e3749b71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification_019e4c07-a6d1-75aa-b670-94f4e3749b71" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableModifiedPrincipalForgiven_019e4c07-a6d1-7efd-bd77-58f2b05477fc" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableModifiedPrincipalForgiven"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_cubi_FinancingReceivableModifiedPrincipalForgiven_019e4c07-a6d1-7efd-bd77-58f2b05477fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPast12Months_019e4c07-a6d1-78b6-9571-97470b758bff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPast12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_019e4c07-a6d1-7c3f-8cb9-232505f1c2fb" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPast12Months_019e4c07-a6d1-78b6-9571-97470b758bff" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESCreditRatingsDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESCreditRatingsDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESCreditRatingsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableRecordedInvestmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-71bd-8756-590a7151dfb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-71bd-8756-590a7151dfb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-71bd-8756-590a7151dfb4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-71bd-8756-590a7151dfb4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-71bd-8756-590a7151dfb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7690-b9f1-6db9743c7871" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d1-71bd-8756-590a7151dfb4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7690-b9f1-6db9743c7871" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:href="cubi-20260630.xsd#cubi_CommercialLoansAndLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7690-b9f1-6db9743c7871" xlink:to="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-792b-ac3e-2f6fa2d589c8" xlink:href="cubi-20260630.xsd#cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:to="loc_cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember_019e4c07-a6d1-792b-ac3e-2f6fa2d589c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-7204-a305-98e8cf9e5fa8" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d1-7204-a305-98e8cf9e5fa8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7937-8136-cf63ac3dd79f" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7937-8136-cf63ac3dd79f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ee0-bcac-3c63ba52b14e" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:to="loc_cubi_CommercialRealEstateNonOwnerOccupiedPortfolioSegmentMember_019e4c07-a6d1-7ee0-bcac-3c63ba52b14e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a6d1-7f48-8acd-2dbc327f1880" xlink:href="cubi-20260630.xsd#cubi_ConstructionPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cubi_CommercialLoansAndLeasesMember_019e4c07-a6d1-72d6-b53d-1ad05593ce0f" xlink:to="loc_cubi_ConstructionPortfolioSegmentMember_019e4c07-a6d1-7f48-8acd-2dbc327f1880" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerLoanMember_019e4c07-a6d1-7f86-8ca9-14d4f4887eec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConsumerLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d1-7690-b9f1-6db9743c7871" xlink:to="loc_us-gaap_ConsumerLoanMember_019e4c07-a6d1-7f86-8ca9-14d4f4887eec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7a96-a283-4c0e4214e038" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsumerLoanMember_019e4c07-a6d1-7f86-8ca9-14d4f4887eec" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_019e4c07-a6d1-7a96-a283-4c0e4214e038" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d2-7b3a-adba-74ad40b85f48" xlink:href="cubi-20260630.xsd#cubi_ManufacturedHousingPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsumerLoanMember_019e4c07-a6d1-7f86-8ca9-14d4f4887eec" xlink:to="loc_cubi_ManufacturedHousingPortfolioSegmentMember_019e4c07-a6d2-7b3a-adba-74ad40b85f48" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d2-78c3-ae25-3cf028a294b8" xlink:href="cubi-20260630.xsd#cubi_InstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsumerLoanMember_019e4c07-a6d1-7f86-8ca9-14d4f4887eec" xlink:to="loc_cubi_InstallmentLoansPortfolioSegmentMember_019e4c07-a6d2-78c3-ae25-3cf028a294b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentAxis_019e4c07-a6d2-73f3-967d-50c2c0ad06a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InternalCreditAssessmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:to="loc_us-gaap_InternalCreditAssessmentAxis_019e4c07-a6d2-73f3-967d-50c2c0ad06a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-73f3-967d-50c2c0ad06a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_019e4c07-a6d2-73f3-967d-50c2c0ad06a9" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-73f3-967d-50c2c0ad06a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_019e4c07-a6d2-73f3-967d-50c2c0ad06a9" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassMember_019e4c07-a6d2-7302-8196-0daf568dda85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PassMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:to="loc_us-gaap_PassMember_019e4c07-a6d2-7302-8196-0daf568dda85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SpecialMentionMember_019e4c07-a6d2-7eae-821e-0b0587a6d55a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SpecialMentionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:to="loc_us-gaap_SpecialMentionMember_019e4c07-a6d2-7eae-821e-0b0587a6d55a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubstandardMember_019e4c07-a6d2-741c-b1b3-6801016873f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubstandardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:to="loc_us-gaap_SubstandardMember_019e4c07-a6d2-741c-b1b3-6801016873f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DoubtfulMember_019e4c07-a6d2-71d4-a045-c93558a611de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DoubtfulMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_019e4c07-a6d2-7174-8f21-3d2108bbd132" xlink:to="loc_us-gaap_DoubtfulMember_019e4c07-a6d2-71d4-a045-c93558a611de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a6d2-776b-9de0-ce1d048586ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a6d2-776b-9de0-ce1d048586ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-776b-9de0-ce1d048586ee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a6d2-776b-9de0-ce1d048586ee" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-776b-9de0-ce1d048586ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-7a0b-a5ef-510ac3c6c798" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis_019e4c07-a6d2-776b-9de0-ce1d048586ee" xlink:to="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-7a0b-a5ef-510ac3c6c798" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialBorrowerMember_019e4c07-a6d2-757d-8fb4-bec3713a29a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialBorrowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-7a0b-a5ef-510ac3c6c798" xlink:to="loc_us-gaap_CommercialBorrowerMember_019e4c07-a6d2-757d-8fb4-bec3713a29a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerBorrowerMember_019e4c07-a6d2-786a-8a96-ccd047ac8d60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConsumerBorrowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfFinancingReceivableTypeOfBorrowerDomain_019e4c07-a6d2-7a0b-a5ef-510ac3c6c798" xlink:to="loc_us-gaap_ConsumerBorrowerMember_019e4c07-a6d2-786a-8a96-ccd047ac8d60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentPerformanceStatusAxis_019e4c07-a6d2-7837-9a42-c3442f99c19a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentPerformanceStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_019e4c07-a6d1-7ee4-bfc8-d8d5fa3ea73b" xlink:to="loc_us-gaap_FinancialInstrumentPerformanceStatusAxis_019e4c07-a6d2-7837-9a42-c3442f99c19a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7837-9a42-c3442f99c19a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentPerformanceStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentPerformanceStatusAxis_019e4c07-a6d2-7837-9a42-c3442f99c19a" xlink:to="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7837-9a42-c3442f99c19a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7f8b-bc47-b38e0d09b855" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentPerformanceStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentPerformanceStatusAxis_019e4c07-a6d2-7837-9a42-c3442f99c19a" xlink:to="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7f8b-bc47-b38e0d09b855" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformingFinancingReceivableMember_019e4c07-a6d2-7c2e-971e-213a1a9e79b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformingFinancingReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7f8b-bc47-b38e0d09b855" xlink:to="loc_us-gaap_PerformingFinancingReceivableMember_019e4c07-a6d2-7c2e-971e-213a1a9e79b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonperformingFinancingReceivableMember_019e4c07-a6d2-7f6d-8625-0aef2fb30a63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonperformingFinancingReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentPerformanceStatusDomain_019e4c07-a6d2-7f8b-bc47-b38e0d09b855" xlink:to="loc_us-gaap_NonperformingFinancingReceivableMember_019e4c07-a6d2-7f6d-8625-0aef2fb30a63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_019e4c07-a6d2-7d0a-83a7-405f9805f7b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_019e4c07-a6d2-7d0a-83a7-405f9805f7b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_019e4c07-a6d2-782f-a592-c9059bf0be6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_019e4c07-a6d2-782f-a592-c9059bf0be6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_019e4c07-a6d2-71a6-a1db-68579b68a4d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_019e4c07-a6d2-71a6-a1db-68579b68a4d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7259-b0fe-63f9504e8c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7259-b0fe-63f9504e8c6a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7644-87b8-a0846393fb78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7644-87b8-a0846393fb78" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7159-89ec-398bca8ea5d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_019e4c07-a6d2-7159-89ec-398bca8ea5d7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_019e4c07-a6d2-7ab4-ba9b-a18fce0f0afe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolving"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_019e4c07-a6d2-7ab4-ba9b-a18fce0f0afe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_019e4c07-a6d2-7584-a86b-e3aa79ad4406" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_019e4c07-a6d2-7584-a86b-e3aa79ad4406" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d2-7822-8f0e-7196183f2489" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d2-7822-8f0e-7196183f2489" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_019e4c07-a6d2-71d8-86a4-c6aa50daccab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_019e4c07-a6d2-71d8-86a4-c6aa50daccab" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-7072-809a-b917a1e7c592" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-7072-809a-b917a1e7c592" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-745e-8855-0ef294f51198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-745e-8855-0ef294f51198" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-725b-b0bd-45a7ffd7555d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-725b-b0bd-45a7ffd7555d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-7c6d-bf99-b2976b4ccef9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-7c6d-bf99-b2976b4ccef9" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-762d-8cf6-083f088c4244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_019e4c07-a6d2-762d-8cf6-083f088c4244" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_019e4c07-a6d2-7fad-8d24-7c3feb81d190" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_019e4c07-a6d2-7fad-8d24-7c3feb81d190" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_019e4c07-a6d2-7579-a3b1-e0ca7875f1ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_019e4c07-a6d2-7579-a3b1-e0ca7875f1ff" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_019e4c07-a6d2-751d-aa19-a26b2d448b6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_019e4c07-a6d2-7ab3-ba40-45ee2d43433e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_019e4c07-a6d2-751d-aa19-a26b2d448b6d" xlink:type="arc" order="17"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoanPurchasesandSalesDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoanPurchasesandSalesDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LOANSANDLEASESRECEIVABLEANDALLOWANCEFORCREDITLOSSESONLOANSANDLEASESScheduleofLoanPurchasesandSalesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a6d2-7312-9ab2-b6235ec0c889" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a6d2-7312-9ab2-b6235ec0c889" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d2-7c58-8589-01f77bb2f7b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_019e4c07-a6d2-7312-9ab2-b6235ec0c889" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d2-7c58-8589-01f77bb2f7b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7c58-8589-01f77bb2f7b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d2-7c58-8589-01f77bb2f7b8" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7c58-8589-01f77bb2f7b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019e4c07-a6d2-7c58-8589-01f77bb2f7b8" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherCommercialAndIndustrialMember_019e4c07-a6d2-744d-b0dd-2c9eb3eb0a75" xlink:href="cubi-20260630.xsd#cubi_OtherCommercialAndIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_OtherCommercialAndIndustrialMember_019e4c07-a6d2-744d-b0dd-2c9eb3eb0a75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ConstructionPortfolioSegmentMember_019ed13b-8055-713c-b346-c7e6f49b7702" xlink:href="cubi-20260630.xsd#cubi_ConstructionPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_ConstructionPortfolioSegmentMember_019ed13b-8055-713c-b346-c7e6f49b7702" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a6d2-7f88-9f98-e7eb75c78f7f" xlink:href="cubi-20260630.xsd#cubi_PersonalInstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_PersonalInstallmentLoansPortfolioSegmentMember_019e4c07-a6d2-7f88-9f98-e7eb75c78f7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_SpecialtyLendingMember_019e4c07-a6d2-72d7-9b69-387c75fffaf1" xlink:href="cubi-20260630.xsd#cubi_SpecialtyLendingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_SpecialtyLendingMember_019e4c07-a6d2-72d7-9b69-387c75fffaf1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d2-7ebe-99c8-cf4146f2e0a7" xlink:href="cubi-20260630.xsd#cubi_MultifamilyPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_MultifamilyPortfolioSegmentMember_019e4c07-a6d2-7ebe-99c8-cf4146f2e0a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialRealEstateOwnerOccupiedMember_019e4c07-a6d2-7ba6-9af8-c3455426322a" xlink:href="cubi-20260630.xsd#cubi_CommercialRealEstateOwnerOccupiedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_CommercialRealEstateOwnerOccupiedMember_019e4c07-a6d2-7ba6-9af8-c3455426322a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherInstallmentLoansPortfolioSegmentMember_019fc871-6f2d-7564-a4b9-4a27d33311d3" xlink:href="cubi-20260630.xsd#cubi_OtherInstallmentLoansPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019e4c07-a6d2-7e5b-b4aa-ddc45a81fe4d" xlink:to="loc_cubi_OtherInstallmentLoansPortfolioSegmentMember_019fc871-6f2d-7564-a4b9-4a27d33311d3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchase_019e4c07-a6d2-75c5-a5fe-b0d26a129427" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestPurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchase_019e4c07-a6d2-75c5-a5fe-b0d26a129427" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestSaleAndReclassificationToHeldForSale_019e4c07-a6d2-7d4c-9194-c0785b53591e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestSaleAndReclassificationToHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestSaleAndReclassificationToHeldForSale_019e4c07-a6d2-7d4c-9194-c0785b53591e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_LoansHeldforinvestmentPurchasePriceasaPercentageofLoansOutstanding_019e4c07-a6d2-7bdc-97a2-0fce9b31392d" xlink:href="cubi-20260630.xsd#cubi_LoansHeldforinvestmentPurchasePriceasaPercentageofLoansOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:to="loc_cubi_LoansHeldforinvestmentPurchasePriceasaPercentageofLoansOutstanding_019e4c07-a6d2-7bdc-97a2-0fce9b31392d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_GainLossOnSaleOfMortgagesAndOtherLoans_019e4c07-a6d2-74a6-af78-c172f8e4475a" xlink:href="cubi-20260630.xsd#cubi_GainLossOnSaleOfMortgagesAndOtherLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_019e4c07-a6d2-7cd7-8eb1-5f89cf31fed1" xlink:to="loc_cubi_GainLossOnSaleOfMortgagesAndOtherLoans_019e4c07-a6d2-74a6-af78-c172f8e4475a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LEASESLesseeNarrativeDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#LEASESLesseeNarrativeDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LEASESLesseeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019e4c07-a6d2-7ea3-9778-71f279fd1fb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019e4c07-a6d2-7ea3-9778-71f279fd1fb4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e4c07-a6d2-7dc8-a351-92e2fb70557f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019e4c07-a6d2-7ea3-9778-71f279fd1fb4" xlink:to="loc_srt_RangeAxis_019e4c07-a6d2-7dc8-a351-92e2fb70557f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7dc8-a351-92e2fb70557f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7dc8-a351-92e2fb70557f" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7dc8-a351-92e2fb70557f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-705b-80cc-bcb6446d14e4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7dc8-a351-92e2fb70557f" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-705b-80cc-bcb6446d14e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e4c07-a6d2-714b-a3cb-d2584dd743bc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-705b-80cc-bcb6446d14e4" xlink:to="loc_srt_MinimumMember_019e4c07-a6d2-714b-a3cb-d2584dd743bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e4c07-a6d2-7a7e-8856-cf7b73d1a133" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-705b-80cc-bcb6446d14e4" xlink:to="loc_srt_MaximumMember_019e4c07-a6d2-7a7e-8856-cf7b73d1a133" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_019e4c07-a6d2-7282-9761-673e21d2d04b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_019e4c07-a6d2-7282-9761-673e21d2d04b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_019e4c07-a6d2-7139-8c0c-0ae67d9d9707" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_019e4c07-a6d2-7139-8c0c-0ae67d9d9707" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_019e4c07-a6d2-7119-87a9-aa4bd4245044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_019e4c07-a6d2-7119-87a9-aa4bd4245044" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_019e4c07-a6d2-789e-baab-340d15bb8f3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e4c07-a6d2-72d5-b321-8276a35cb7e2" xlink:to="loc_us-gaap_OperatingLeasePayments_019e4c07-a6d2-789e-baab-340d15bb8f3b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/LEASESLessorNarrativeDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#LEASESLessorNarrativeDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/LEASESLessorNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionLineItems_019e4c07-a6d2-7eaa-956c-123a3821f291" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LessorLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionTable_019e4c07-a6d2-7b81-8a80-d337ce7dd5b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LessorLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019e4c07-a6d2-7eaa-956c-123a3821f291" xlink:to="loc_us-gaap_LessorLeaseDescriptionTable_019e4c07-a6d2-7b81-8a80-d337ce7dd5b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e4c07-a6d2-7249-971e-9a76188f90c4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LessorLeaseDescriptionTable_019e4c07-a6d2-7b81-8a80-d337ce7dd5b2" xlink:to="loc_srt_RangeAxis_019e4c07-a6d2-7249-971e-9a76188f90c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7249-971e-9a76188f90c4_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7249-971e-9a76188f90c4" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7249-971e-9a76188f90c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7e54-877e-d5f6805202b1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7249-971e-9a76188f90c4" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7e54-877e-d5f6805202b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e4c07-a6d2-7911-ba64-ff9d33aecac1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-7e54-877e-d5f6805202b1" xlink:to="loc_srt_MinimumMember_019e4c07-a6d2-7911-ba64-ff9d33aecac1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e4c07-a6d2-757e-87f6-7dd62c2e0b77" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-7e54-877e-d5f6805202b1" xlink:to="loc_srt_MaximumMember_019e4c07-a6d2-757e-87f6-7dd62c2e0b77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorDirectFinancingLeaseTermOfContract1_019e4c07-a6d2-7ce7-9ca8-459bf0d1bb98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LessorDirectFinancingLeaseTermOfContract1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019e4c07-a6d2-7eaa-956c-123a3821f291" xlink:to="loc_us-gaap_LessorDirectFinancingLeaseTermOfContract1_019e4c07-a6d2-7ce7-9ca8-459bf0d1bb98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesTypeAndDirectFinancingLeasesInterestIncome_019e4c07-a6d2-7e2b-91d6-b4deb718cc3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalesTypeAndDirectFinancingLeasesInterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019e4c07-a6d2-7eaa-956c-123a3821f291" xlink:to="loc_us-gaap_SalesTypeAndDirectFinancingLeasesInterestIncome_019e4c07-a6d2-7e2b-91d6-b4deb718cc3b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DEPOSITSNarrativeDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DEPOSITSNarrativeDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DEPOSITSNarrativeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositLiabilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeDepositsTable_019e4c07-a6d2-714c-a637-dafb7d51425f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimeDepositsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:to="loc_us-gaap_TimeDepositsTable_019e4c07-a6d2-714c-a637-dafb7d51425f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TimeDepositsTable_019e4c07-a6d2-714c-a637-dafb7d51425f" xlink:to="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-72fe-9d91-9fc03c6d72ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-70fd-a6c7-9e2a18e08cc8" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-72fe-9d91-9fc03c6d72ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a6d2-7f9b-8d52-830c2773cf32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-72fe-9d91-9fc03c6d72ec" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_019e4c07-a6d2-7f9b-8d52-830c2773cf32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit_019e4c07-a6d2-7d99-b04a-ec851c77d150" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:to="loc_us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit_019e4c07-a6d2-7d99-b04a-ec851c77d150" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositLiabilitiesReclassifiedAsLoansReceivable1_019e4c07-a6d2-7078-acc5-3ca638d3b36b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositLiabilitiesReclassifiedAsLoansReceivable1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:to="loc_us-gaap_DepositLiabilitiesReclassifiedAsLoansReceivable1_019e4c07-a6d2-7078-acc5-3ca638d3b36b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DepositsStateAndMunicipalSecuredByCollateral_019e4c07-a6d2-705b-905e-c3cf520ec11e" xlink:href="cubi-20260630.xsd#cubi_DepositsStateAndMunicipalSecuredByCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:to="loc_cubi_DepositsStateAndMunicipalSecuredByCollateral_019e4c07-a6d2-705b-905e-c3cf520ec11e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds_019e4c07-a6d2-7ac7-b02f-1f0cdbad7be2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepositLiabilityLineItems_019e4c07-a6d2-7d3e-8190-2b5d4f3b0959" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds_019e4c07-a6d2-7ac7-b02f-1f0cdbad7be2" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/BORROWINGSSummaryofBancorpsShorttermBorrowingsDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#BORROWINGSSummaryofBancorpsShorttermBorrowingsDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/BORROWINGSSummaryofBancorpsShorttermBorrowingsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtLineItems_019e4c07-a6d2-74e5-b066-b2481cf76983" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShortTermDebtTable_019e4c07-a6d2-7e49-96a9-adb5ae65ff55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShortTermDebtTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019e4c07-a6d2-74e5-b066-b2481cf76983" xlink:to="loc_us-gaap_ScheduleOfShortTermDebtTable_019e4c07-a6d2-7e49-96a9-adb5ae65ff55" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-7e7c-afeb-84e0e683c031" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_019e4c07-a6d2-7e49-96a9-adb5ae65ff55" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-7e7c-afeb-84e0e683c031" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-7e7c-afeb-84e0e683c031_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-7e7c-afeb-84e0e683c031" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-7e7c-afeb-84e0e683c031_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-745c-a477-8b367019d8a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-7e7c-afeb-84e0e683c031" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-745c-a477-8b367019d8a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-77c7-b016-e0a775835916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-745c-a477-8b367019d8a2" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-77c7-b016-e0a775835916" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsPurchasedMember_019e4c07-a6d2-78c5-b8be-7473366c16cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalFundsPurchasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-745c-a477-8b367019d8a2" xlink:to="loc_us-gaap_FederalFundsPurchasedMember_019e4c07-a6d2-78c5-b8be-7473366c16cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShorttermDebtMaximumMonthendOutstandingAmount_019e4c07-a6d2-716c-8ff2-f0a8c6df8da2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShorttermDebtMaximumMonthendOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019e4c07-a6d2-74e5-b066-b2481cf76983" xlink:to="loc_us-gaap_ShorttermDebtMaximumMonthendOutstandingAmount_019e4c07-a6d2-716c-8ff2-f0a8c6df8da2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShorttermDebtAverageOutstandingAmount_019e4c07-a6d2-774f-b5af-88747e0ce2f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShorttermDebtAverageOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019e4c07-a6d2-74e5-b066-b2481cf76983" xlink:to="loc_us-gaap_ShorttermDebtAverageOutstandingAmount_019e4c07-a6d2-774f-b5af-88747e0ce2f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_019e4c07-a6d2-79cb-a731-1c754b34cd1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019e4c07-a6d2-74e5-b066-b2481cf76983" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_019e4c07-a6d2-79cb-a731-1c754b34cd1a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/BORROWINGSNarrativeDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#BORROWINGSNarrativeDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/BORROWINGSNarrativeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-710e-b93a-89521fc616dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7f6e-b55d-f19d682a074c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-710e-b93a-89521fc616dc" xlink:to="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7f6e-b55d-f19d682a074c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-79ea-8f82-8e5978f73536" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7f6e-b55d-f19d682a074c" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-79ea-8f82-8e5978f73536" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-79ea-8f82-8e5978f73536_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-79ea-8f82-8e5978f73536" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-79ea-8f82-8e5978f73536_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-7d4a-8920-40512d827fc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e4c07-a6d2-79ea-8f82-8e5978f73536" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-7d4a-8920-40512d827fc5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsPurchasedMember_019e4c07-a6d2-7c9e-a34d-1b2b2106a70c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalFundsPurchasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e4c07-a6d2-7d4a-8920-40512d827fc5" xlink:to="loc_us-gaap_FederalFundsPurchasedMember_019e4c07-a6d2-7c9e-a34d-1b2b2106a70c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e4c07-a6d2-7b77-9aa2-6ef8298ee3b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-710e-b93a-89521fc616dc" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e4c07-a6d2-7b77-9aa2-6ef8298ee3b1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/BORROWINGSFHLBandFRBAdvancesDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#BORROWINGSFHLBandFRBAdvancesDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/BORROWINGSFHLBandFRBAdvancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7a50-974f-2054c31f6b8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7a50-974f-2054c31f6b8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-7443-b71e-afab9d79144f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7a50-974f-2054c31f6b8a" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-7443-b71e-afab9d79144f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7443-b71e-afab9d79144f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-7443-b71e-afab9d79144f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7443-b71e-afab9d79144f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7ee7-939f-9b1cf13b05e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-7443-b71e-afab9d79144f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7ee7-939f-9b1cf13b05e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7957-98a9-d6454c368f60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7ee7-939f-9b1cf13b05e9" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7957-98a9-d6454c368f60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-71ab-a0ef-974749da4e5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7a50-974f-2054c31f6b8a" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-71ab-a0ef-974749da4e5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-71ab-a0ef-974749da4e5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-71ab-a0ef-974749da4e5b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-71ab-a0ef-974749da4e5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7958-88a8-6d2d5fc1bb35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-71ab-a0ef-974749da4e5b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7958-88a8-6d2d5fc1bb35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FHLBAdvanceDueMarch2028Member_019e4c07-a6d2-7279-9567-ca5eb8e4fb4b" xlink:href="cubi-20260630.xsd#cubi_FHLBAdvanceDueMarch2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7958-88a8-6d2d5fc1bb35" xlink:to="loc_cubi_FHLBAdvanceDueMarch2028Member_019e4c07-a6d2-7279-9567-ca5eb8e4fb4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FHLBAdvanceDueDecember2028Member_019e4c07-a6d2-734c-89bd-13385b9a82ef" xlink:href="cubi-20260630.xsd#cubi_FHLBAdvanceDueDecember2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7958-88a8-6d2d5fc1bb35" xlink:to="loc_cubi_FHLBAdvanceDueDecember2028Member_019e4c07-a6d2-734c-89bd-13385b9a82ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-7bf7-bba8-edf3bdab4579" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-7a50-974f-2054c31f6b8a" xlink:to="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-7bf7-bba8-edf3bdab4579" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-7bf7-bba8-edf3bdab4579_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-7bf7-bba8-edf3bdab4579" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-7bf7-bba8-edf3bdab4579_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-7c03-ab88-aec401b65232" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_019e4c07-a6d2-7bf7-bba8-edf3bdab4579" xlink:to="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-7c03-ab88-aec401b65232" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_QualifyingAssetsPledgedAsCollateralMember_019e4c07-a6d2-7c7c-903a-e7389d2c5ae9" xlink:href="cubi-20260630.xsd#cubi_QualifyingAssetsPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_019e4c07-a6d2-7c03-ab88-aec401b65232" xlink:to="loc_cubi_QualifyingAssetsPledgedAsCollateralMember_019e4c07-a6d2-7c7c-903a-e7389d2c5ae9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019e4c07-a6d2-73d6-93ce-db6f6a072907" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_LongTermDebt_019e4c07-a6d2-73d6-93ce-db6f6a072907" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e4c07-a6d2-791e-b111-6dcc692ee545" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e4c07-a6d2-791e-b111-6dcc692ee545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_019e4c07-a6d2-758c-b5bc-2ef91b3a14fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvancesFromFederalHomeLoanBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_019e4c07-a6d2-758c-b5bc-2ef91b3a14fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease_019e4c07-a6d2-7fa5-9c69-844f7b62dbf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease_019e4c07-a6d2-7fa5-9c69-844f7b62dbf3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueInRemainderOfFiscalYear_019e4c07-a6d2-7ae0-8e22-11285fccee25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueInRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueInRemainderOfFiscalYear_019e4c07-a6d2-7ae0-8e22-11285fccee25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate_019e4c07-a6d2-79ed-adb6-aba7af393e20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate_019e4c07-a6d2-79ed-adb6-aba7af393e20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate_019e4c07-a6d2-7620-a87c-e8657984e1bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromOneToTwoYearsOfBalanceSheetDate_019e4c07-a6d2-7620-a87c-e8657984e1bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromTwoToThreeYearsOfBalanceSheetDate_019e4c07-a6d2-7bf0-894e-9c5446b17111" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromTwoToThreeYearsOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromTwoToThreeYearsOfBalanceSheetDate_019e4c07-a6d2-7bf0-894e-9c5446b17111" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromThreeToFourYearsOfBalanceSheetDate_019e4c07-a6d2-77d4-b3af-40f67d796d9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromThreeToFourYearsOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromThreeToFourYearsOfBalanceSheetDate_019e4c07-a6d2-77d4-b3af-40f67d796d9e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromFourToFiveYearsOfBalanceSheetDate_019e4c07-a6d2-7656-9821-552b084d4fae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromFourToFiveYearsOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAbstract_019e4c07-a6d2-7ca0-9c88-8ca1509c3b47" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueFromFourToFiveYearsOfBalanceSheetDate_019e4c07-a6d2-7656-9821-552b084d4fae" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_019e4c07-a6d2-7158-ba39-94e546bd1c83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvancesFromFederalHomeLoanBanks"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FederalHomeLoanBankAdvanceMaturityAverageInterestRateRemainderOfFiscalYear_019e4c07-a6d2-7da3-a9c8-58935322f63c" xlink:href="cubi-20260630.xsd#cubi_FederalHomeLoanBankAdvanceMaturityAverageInterestRateRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_cubi_FederalHomeLoanBankAdvanceMaturityAverageInterestRateRemainderOfFiscalYear_019e4c07-a6d2-7da3-a9c8-58935322f63c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate_019e4c07-a6d2-7c3a-b8da-42669ac50580" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate_019e4c07-a6d2-7c3a-b8da-42669ac50580" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate_019e4c07-a6d2-71aa-a227-d618b141a9de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOneToTwoYearsFromBalanceSheetDate_019e4c07-a6d2-71aa-a227-d618b141a9de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateTwoToThreeYearsFromBalanceSheetDate_019e4c07-a6d2-7ae6-b223-5588bb655fe4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateTwoToThreeYearsFromBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateTwoToThreeYearsFromBalanceSheetDate_019e4c07-a6d2-7ae6-b223-5588bb655fe4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateThreeToFourYearsFromBalanceSheetDate_019e4c07-a6d2-76e7-a07e-67dfef45fbb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateThreeToFourYearsFromBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateThreeToFourYearsFromBalanceSheetDate_019e4c07-a6d2-76e7-a07e-67dfef45fbb0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateFourToFiveYearsFromBalanceSheetDate_019e4c07-a6d2-78e8-bcd5-4bd3b3c4e361" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateFourToFiveYearsFromBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateOfAmountsDueAbstract_019e4c07-a6d2-7266-bc8f-6e6989f2c6b7" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryAverageInterestRateFourToFiveYearsFromBalanceSheetDate_019e4c07-a6d2-78e8-bcd5-4bd3b3c4e361" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable_019e4c07-a6d2-772b-9ca6-179045549bb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable_019e4c07-a6d2-772b-9ca6-179045549bb4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FederalReserveBankMaximumAmountAvailable_019e4c07-a6d2-73be-8f40-9ebdb788fc7c" xlink:href="cubi-20260630.xsd#cubi_FederalReserveBankMaximumAmountAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_cubi_FederalReserveBankMaximumAmountAvailable_019e4c07-a6d2-73be-8f40-9ebdb788fc7c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d2-7e8a-8278-a0f61f2515d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7080-8a00-4899c7f70f62" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_019e4c07-a6d2-7e8a-8278-a0f61f2515d0" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/BORROWINGSLongtermDebtDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#BORROWINGSLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/BORROWINGSLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-760f-bc35-12b4c569c24c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-760f-bc35-12b4c569c24c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-734c-9380-e8b179cc4281" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-760f-bc35-12b4c569c24c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-734c-9380-e8b179cc4281" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-734c-9380-e8b179cc4281_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-734c-9380-e8b179cc4281" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-734c-9380-e8b179cc4281_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-734c-9380-e8b179cc4281" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MaturingAugust2031Member_019e4c07-a6d2-7bdf-9cdf-d6f1d4964075" xlink:href="cubi-20260630.xsd#cubi_MaturingAugust2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:to="loc_cubi_MaturingAugust2031Member_019e4c07-a6d2-7bdf-9cdf-d6f1d4964075" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MaturingJanuary2036Member_019e4c07-a6d2-7a5b-98ab-2e03416ff6d6" xlink:href="cubi-20260630.xsd#cubi_MaturingJanuary2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:to="loc_cubi_MaturingJanuary2036Member_019e4c07-a6d2-7a5b-98ab-2e03416ff6d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MaturingDecember2034Member_019e4c07-a6d2-72d4-a90d-8b163f7de0f9" xlink:href="cubi-20260630.xsd#cubi_MaturingDecember2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:to="loc_cubi_MaturingDecember2034Member_019e4c07-a6d2-72d4-a90d-8b163f7de0f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MaturingJune2029Member_019e4c07-a6d2-7bde-9b85-4ca80de137e5" xlink:href="cubi-20260630.xsd#cubi_MaturingJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:to="loc_cubi_MaturingJune2029Member_019e4c07-a6d2-7bde-9b85-4ca80de137e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MaturingDecember2035Member_019e4c07-a6d2-7df5-acb9-39e10d755668" xlink:href="cubi-20260630.xsd#cubi_MaturingDecember2035Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7be8-8d06-d8ccd094f62b" xlink:to="loc_cubi_MaturingDecember2035Member_019e4c07-a6d2-7df5-acb9-39e10d755668" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-76a8-bb07-be88f9e96039" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e4c07-a6d2-760f-bc35-12b4c569c24c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-76a8-bb07-be88f9e96039" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-76a8-bb07-be88f9e96039_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-76a8-bb07-be88f9e96039" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-76a8-bb07-be88f9e96039_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7bb9-a4b0-0f3f57e0e1e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e4c07-a6d2-76a8-bb07-be88f9e96039" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7bb9-a4b0-0f3f57e0e1e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e4c07-a6d2-7869-82e9-448420635216" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7bb9-a4b0-0f3f57e0e1e7" xlink:to="loc_us-gaap_SeniorNotesMember_019e4c07-a6d2-7869-82e9-448420635216" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorSubordinatedNotesMember_019e4c07-a6d2-7e00-9b54-2e237a17d721" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorSubordinatedNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e4c07-a6d2-7bb9-a4b0-0f3f57e0e1e7" xlink:to="loc_us-gaap_SeniorSubordinatedNotesMember_019e4c07-a6d2-7e00-9b54-2e237a17d721" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019e4c07-a6d2-7f58-b0d1-bfbbc5d51d32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_LongTermDebt_019e4c07-a6d2-7f58-b0d1-bfbbc5d51d32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DebtInstrumentFaceAmountPercentage_019e4c07-a6d2-72b6-957f-f09c520cc21e" xlink:href="cubi-20260630.xsd#cubi_DebtInstrumentFaceAmountPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_cubi_DebtInstrumentFaceAmountPercentage_019e4c07-a6d2-72b6-957f-f09c520cc21e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e4c07-a6d2-79d1-bfb0-f701b1863a3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e4c07-a6d2-79d1-bfb0-f701b1863a3a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e4c07-a6d2-7157-922f-3e2e6f0d2d4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e4c07-a6d2-7157-922f-3e2e6f0d2d4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e4c07-a6d2-7167-a076-f7cb174ac16c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e4c07-a6d2-7167-a076-f7cb174ac16c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentVariableInterestRateTypeExtensibleEnumeration_019e4c07-a6d2-7848-9efb-d8bb6a394dbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentVariableInterestRateTypeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_us-gaap_DebtInstrumentVariableInterestRateTypeExtensibleEnumeration_019e4c07-a6d2-7848-9efb-d8bb6a394dbb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PreferredStockDividendRateBasisSpreadofVariableRate_019e4c07-a6d2-7a36-b407-5e46737ba925" xlink:href="cubi-20260630.xsd#cubi_PreferredStockDividendRateBasisSpreadofVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e4c07-a6d2-7604-a172-e8471650611f" xlink:to="loc_cubi_PreferredStockDividendRateBasisSpreadofVariableRate_019e4c07-a6d2-7a36-b407-5e46737ba925" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/SHAREHOLDERSEQUITYDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#SHAREHOLDERSEQUITYDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/SHAREHOLDERSEQUITYDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalUnitLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCapitalUnitsTable_019e4c07-a6d2-7d23-bcbf-839c1e8f68e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCapitalUnitsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_ScheduleOfCapitalUnitsTable_019e4c07-a6d2-7d23-bcbf-839c1e8f68e7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramAxis_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCapitalUnitsTable_019e4c07-a6d2-7d23-bcbf-839c1e8f68e7" xlink:to="loc_srt_ShareRepurchaseProgramAxis_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019e4c07-a6d2-7015-b408-df2e7cc69bdb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019e4c07-a6d2-77fd-a5fa-c1c9cdc75393" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019e4c07-a6d2-7015-b408-df2e7cc69bdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ShareRepurchaseProgramMember_019e4c07-a6d2-7122-ac71-76be001ccfb4" xlink:href="cubi-20260630.xsd#cubi_ShareRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_019e4c07-a6d2-7015-b408-df2e7cc69bdb" xlink:to="loc_cubi_ShareRepurchaseProgramMember_019e4c07-a6d2-7122-ac71-76be001ccfb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a6d2-7cbf-ae84-120de1c765d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCapitalUnitsTable_019e4c07-a6d2-7d23-bcbf-839c1e8f68e7" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a6d2-7cbf-ae84-120de1c765d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a6d2-7cbf-ae84-120de1c765d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a6d2-7cbf-ae84-120de1c765d9" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a6d2-7cbf-ae84-120de1c765d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e4c07-a6d2-7bed-b0b0-cba1df946cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e4c07-a6d2-7cbf-ae84-120de1c765d9" xlink:to="loc_us-gaap_ClassOfStockDomain_019e4c07-a6d2-7bed-b0b0-cba1df946cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesEPreferredStockMember_019e4c07-a6d2-756a-8d2a-06efb14b06ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesEPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e4c07-a6d2-7bed-b0b0-cba1df946cbc" xlink:to="loc_us-gaap_SeriesEPreferredStockMember_019e4c07-a6d2-756a-8d2a-06efb14b06ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_019e4c07-a6d2-7c19-ada4-4015ab671cc6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_019e4c07-a6d2-7c19-ada4-4015ab671cc6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ShareRepurchaseProgramExtensionPeriod_019e4c07-a6d2-7f65-82ef-9a1d09fb3147" xlink:href="cubi-20260630.xsd#cubi_ShareRepurchaseProgramExtensionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_cubi_ShareRepurchaseProgramExtensionPeriod_019e4c07-a6d2-7f65-82ef-9a1d09fb3147" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_019e4c07-a6d2-7d12-a876-441a640133c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_019e4c07-a6d2-7d12-a876-441a640133c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_019e4c07-a6d2-7611-a1ec-1bbc82e3b78a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_019e4c07-a6d2-7611-a1ec-1bbc82e3b78a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e4c07-a6d2-7fb9-9807-52a2827e92ce" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e4c07-a6d2-7fb9-9807-52a2827e92ce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock_019e4c07-a6d2-707a-b54c-05693443b428" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock_019e4c07-a6d2-707a-b54c-05693443b428" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockRedemptionPricePerShare_019e4c07-a6d2-7ee2-b4a1-fa3718bcd63c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockRedemptionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_PreferredStockRedemptionPricePerShare_019e4c07-a6d2-7ee2-b4a1-fa3718bcd63c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockRedemptionAmount_019ed1d3-cb17-74fb-b795-8ffce730fa83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockRedemptionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_PreferredStockRedemptionAmount_019ed1d3-cb17-74fb-b795-8ffce730fa83" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockRedemptionPremium_019ed1d1-dce0-7b70-ab07-c7cc71041b04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockRedemptionPremium"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_PreferredStockRedemptionPremium_019ed1d1-dce0-7b70-ab07-c7cc71041b04" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_019e4c07-a6d2-7876-95d2-ff66f14b6af9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalUnitLineItems_019e4c07-a6d2-7d3d-83ca-082e38d4d6e6" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_019e4c07-a6d2-7876-95d2-ff66f14b6af9" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/SHAREBASEDCOMPENSATIONNarrativeDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#SHAREBASEDCOMPENSATIONNarrativeDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/SHAREBASEDCOMPENSATIONNarrativeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-7a47-b763-3c4be40fb3b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-7a47-b763-3c4be40fb3b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7b58-acb3-26a63ec38ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-7a47-b763-3c4be40fb3b2" xlink:to="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7b58-acb3-26a63ec38ebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7b58-acb3-26a63ec38ebc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7b58-acb3-26a63ec38ebc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7b58-acb3-26a63ec38ebc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7da4-a791-f0fb4b2b9e43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7b58-acb3-26a63ec38ebc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7da4-a791-f0fb4b2b9e43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e4c07-a6d2-79f9-9b5a-6f708bae9f93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7da4-a791-f0fb4b2b9e43" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e4c07-a6d2-79f9-9b5a-6f708bae9f93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_PerformanceBasedRestrictedStockUnitsMember_019e4c07-a6d2-7f40-8a1d-9904db57c8f5" xlink:href="cubi-20260630.xsd#cubi_PerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7da4-a791-f0fb4b2b9e43" xlink:to="loc_cubi_PerformanceBasedRestrictedStockUnitsMember_019e4c07-a6d2-7f40-8a1d-9904db57c8f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019e4c07-a6d2-7a8c-8a74-0c73b8d945df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-7a47-b763-3c4be40fb3b2" xlink:to="loc_us-gaap_VestingAxis_019e4c07-a6d2-7a8c-8a74-0c73b8d945df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e4c07-a6d2-7a8c-8a74-0c73b8d945df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019e4c07-a6d2-7a8c-8a74-0c73b8d945df" xlink:to="loc_us-gaap_VestingDomain_019e4c07-a6d2-7a8c-8a74-0c73b8d945df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019e4c07-a6d2-7a8c-8a74-0c73b8d945df" xlink:to="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019e4c07-a6d2-7431-b72b-d63d963a6cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019e4c07-a6d2-7431-b72b-d63d963a6cd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019e4c07-a6d2-7259-8665-877324967299" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019e4c07-a6d2-7259-8665-877324967299" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_019e4c07-a6d2-7b3a-8cf3-3419b9e51a54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_019e4c07-a6d2-7b3a-8cf3-3419b9e51a54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_WaterfallMember_019e4c07-a6d2-75df-bc4a-e65abbaa76ed" xlink:href="cubi-20260630.xsd#cubi_WaterfallMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:to="loc_cubi_WaterfallMember_019e4c07-a6d2-75df-bc4a-e65abbaa76ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CliffMember_019e4c07-a6d2-76f6-8aec-a4956342040f" xlink:href="cubi-20260630.xsd#cubi_CliffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e4c07-a6d2-755f-be71-8251e77b5ac0" xlink:to="loc_cubi_CliffMember_019e4c07-a6d2-76f6-8aec-a4956342040f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019ed1d8-7a2d-7476-ada0-3095b7151431" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-7a47-b763-3c4be40fb3b2" xlink:to="loc_us-gaap_PlanNameAxis_019ed1d8-7a2d-7476-ada0-3095b7151431" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019ed1d8-7a2d-7476-ada0-3095b7151431_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019ed1d8-7a2d-7476-ada0-3095b7151431" xlink:to="loc_us-gaap_PlanNameDomain_019ed1d8-7a2d-7476-ada0-3095b7151431_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019ed1d8-7a2d-7f8b-8d9c-6d91856d62ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019ed1d8-7a2d-7476-ada0-3095b7151431" xlink:to="loc_us-gaap_PlanNameDomain_019ed1d8-7a2d-7f8b-8d9c-6d91856d62ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_A2004And2019PlanMember_019ed1d8-7a2d-77a1-8799-efdb93c4d1d0" xlink:href="cubi-20260630.xsd#cubi_A2004And2019PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019ed1d8-7a2d-7f8b-8d9c-6d91856d62ed" xlink:to="loc_cubi_A2004And2019PlanMember_019ed1d8-7a2d-77a1-8799-efdb93c4d1d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019e4c07-a6d2-796a-ae08-4ce5745079f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019e4c07-a6d2-796a-ae08-4ce5745079f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e4c07-a6d2-7cc9-962e-361d0ff53b80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e4c07-a6d2-7cc9-962e-361d0ff53b80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e4c07-a6d2-7475-9f88-3abf9f33c92d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e4c07-a6d2-7475-9f88-3abf9f33c92d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e4c07-a6d2-79ef-842d-c83421bfcce2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e4c07-a6d2-79ef-842d-c83421bfcce2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e4c07-a6d2-70f0-8421-29e591f1c9d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e4c07-a6d2-70f0-8421-29e591f1c9d6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e4c07-a6d2-79d0-a78f-058837ce8e8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e4c07-a6d2-79d0-a78f-058837ce8e8b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingDays_019e4c07-a6d2-75e3-a6c5-8b8590aec4c0" xlink:href="cubi-20260630.xsd#cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingDays_019e4c07-a6d2-75e3-a6c5-8b8590aec4c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingPrice_019e4c07-a6d2-791b-9b2f-eb08b57e7a47" xlink:href="cubi-20260630.xsd#cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_cubi_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdTradingPrice_019e4c07-a6d2-791b-9b2f-eb08b57e7a47" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_019e4c07-a6d2-776a-bace-ede22a4d69aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7d37-8182-08a608c49737" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_019e4c07-a6d2-776a-bace-ede22a4d69aa" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/SHAREBASEDCOMPENSATIONStatusofRestrictedStockDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#SHAREBASEDCOMPENSATIONStatusofRestrictedStockDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/SHAREBASEDCOMPENSATIONStatusofRestrictedStockDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7b31-8179-f5f8e529d8ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-70f6-943e-81ddd960fcef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7b31-8179-f5f8e529d8ce" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-70f6-943e-81ddd960fcef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7680-a762-932af45e60cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e4c07-a6d2-70f6-943e-81ddd960fcef" xlink:to="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7680-a762-932af45e60cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7680-a762-932af45e60cd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7680-a762-932af45e60cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-7680-a762-932af45e60cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-71bc-bba1-729b0f8519b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e4c07-a6d2-7680-a762-932af45e60cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-71bc-bba1-729b0f8519b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e4c07-a6d2-72aa-80cf-a55d25bde72f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e4c07-a6d2-71bc-bba1-729b0f8519b2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e4c07-a6d2-72aa-80cf-a55d25bde72f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7b31-8179-f5f8e529d8ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e4c07-a6d2-7854-ad1a-7041dd632ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e4c07-a6d2-7854-ad1a-7041dd632ff9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e4c07-a6d2-7a00-b8ba-723fbfddb6f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e4c07-a6d2-7a00-b8ba-723fbfddb6f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e4c07-a6d2-77f8-9e00-fa23b8ea1caf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e4c07-a6d2-77f8-9e00-fa23b8ea1caf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e4c07-a6d2-7aea-a174-d46153761feb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e4c07-a6d2-7475-b634-905db572baed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e4c07-a6d2-7aea-a174-d46153761feb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e4c07-a6d2-7cd3-ab3e-bd55db5fe9e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e4c07-a6d2-7b31-8179-f5f8e529d8ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e4c07-a6d2-787d-89de-921e136016f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e4c07-a6d2-787d-89de-921e136016f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e4c07-a6d2-7a8c-9449-cfd46a94ac6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e4c07-a6d2-7a8c-9449-cfd46a94ac6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e4c07-a6d2-76d8-ab3b-aab4517397c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e4c07-a6d2-76d8-ab3b-aab4517397c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e4c07-a6d2-7e5f-ad0c-f1d654de92f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e4c07-a6d2-7fad-be6f-74be94076102" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e4c07-a6d2-7e5f-ad0c-f1d654de92f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e4c07-a6d2-715c-9111-29f88d5b9219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/REGULATORYCAPITALSummaryofCapitalAmountsTier1RiskBasedandTier1LeveragedRatiosDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#REGULATORYCAPITALSummaryofCapitalAmountsTier1RiskBasedandTier1LeveragedRatiosDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/REGULATORYCAPITALSummaryofCapitalAmountsTier1RiskBasedandTier1LeveragedRatiosDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_019e4c07-a6d2-70ae-8b15-8d1ce474619a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_019e4c07-a6d2-70ae-8b15-8d1ce474619a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_019e4c07-a6d2-70ae-8b15-8d1ce474619a" xlink:to="loc_dei_LegalEntityAxis_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3" xlink:to="loc_dei_EntityDomain_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e4c07-a6d2-7502-bead-1bacce73a736" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e4c07-a6d2-70c1-b15e-d0c760d2b1a3" xlink:to="loc_dei_EntityDomain_019e4c07-a6d2-7502-bead-1bacce73a736" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CustomersBankMember_019e4c07-a6d2-7767-9a3a-0a66cbb7bb9b" xlink:href="cubi-20260630.xsd#cubi_CustomersBankMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e4c07-a6d2-7502-bead-1bacce73a736" xlink:to="loc_cubi_CustomersBankMember_019e4c07-a6d2-7767-9a3a-0a66cbb7bb9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonEquityTierOneCapital_019e4c07-a6d2-7050-838d-8126e6ad8f87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonEquityTierOneCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CommonEquityTierOneCapital_019e4c07-a6d2-7050-838d-8126e6ad8f87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapital_019e4c07-a6d2-790a-9218-74b4cf293def" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapital_019e4c07-a6d2-790a-9218-74b4cf293def" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Capital_019e4c07-a6d2-75d2-ade3-e96819e2b403" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Capital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_Capital_019e4c07-a6d2-75d2-ade3-e96819e2b403" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapital_019e4c07-a6d2-7546-acfb-bddda08439d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapital_019e4c07-a6d2-7546-acfb-bddda08439d3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneCommonCapitaltoRiskWeightedAssets_019e4c07-a6d2-7653-8a23-06c6425f6674" xlink:href="cubi-20260630.xsd#cubi_TierOneCommonCapitaltoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneCommonCapitaltoRiskWeightedAssets_019e4c07-a6d2-7653-8a23-06c6425f6674" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets_019e4c07-a6d2-7bc4-9393-79a59ec7145c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets_019e4c07-a6d2-7bc4-9393-79a59ec7145c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalToRiskWeightedAssets_019e4c07-a6d2-7371-99ac-53fc781c81ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CapitalToRiskWeightedAssets_019e4c07-a6d2-7371-99ac-53fc781c81ad" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalToAverageAssets_019e4c07-a6d2-7fa6-8ee4-c7e039bee2fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapitalToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapitalToAverageAssets_019e4c07-a6d2-7fa6-8ee4-c7e039bee2fd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonEquityTierOneCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7ebb-8129-ff635491078e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonEquityTierOneCapitalRequiredForCapitalAdequacy"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CommonEquityTierOneCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7ebb-8129-ff635491078e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-730b-b09d-f5cddb140d96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-730b-b09d-f5cddb140d96" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7fa7-83c7-32d635868a2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalRequiredForCapitalAdequacy"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7fa7-83c7-32d635868a2f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7908-9603-66d9c8c77b27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy_019e4c07-a6d2-7908-9603-66d9c8c77b27" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets_019e4c07-a6d2-752f-976b-65b2d3dee807" xlink:href="cubi-20260630.xsd#cubi_TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets_019e4c07-a6d2-752f-976b-65b2d3dee807" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets_019e4c07-a6d2-7012-a8ca-6977259ebbbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets_019e4c07-a6d2-7012-a8ca-6977259ebbbb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets_019e4c07-a6d2-73f3-992e-1a66ee0bcc9a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets_019e4c07-a6d2-73f3-992e-1a66ee0bcc9a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets_019e4c07-a6d2-75ab-86be-597bfdd3b8f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets_019e4c07-a6d2-75ab-86be-597bfdd3b8f9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonEquityTierOneCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-78da-995d-c826a8cd8eb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonEquityTierOneCapitalRequiredToBeWellCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CommonEquityTierOneCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-78da-995d-c826a8cd8eb3" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-7fcb-a8fa-a43ccd794f0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-7fcb-a8fa-a43ccd794f0d" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredToBeWellCapitalized_019e4c07-a6d2-72e5-8849-1b41c9b92b4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalRequiredToBeWellCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CapitalRequiredToBeWellCapitalized_019e4c07-a6d2-72e5-8849-1b41c9b92b4c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-71f5-8ce4-a63868bbac99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized_019e4c07-a6d2-71f5-8ce4-a63868bbac99" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets_019e4c07-a6d2-7589-9241-8fee45a8fb87" xlink:href="cubi-20260630.xsd#cubi_TierOneCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets_019e4c07-a6d2-7589-9241-8fee45a8fb87" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_019e4c07-a6d2-7238-9c64-310cbad2f6f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_019e4c07-a6d2-7238-9c64-310cbad2f6f9" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_019e4c07-a6d2-7eeb-996e-d3f9a130b45a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_019e4c07-a6d2-7eeb-996e-d3f9a130b45a" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets_019e4c07-a6d2-7032-a223-cc03bdb5b581" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets_019e4c07-a6d2-7032-a223-cc03bdb5b581" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommonEquityTierOneCapitalRequiredforBaselIII_019e4c07-a6d2-74f7-9786-d836a0cc4496" xlink:href="cubi-20260630.xsd#cubi_CommonEquityTierOneCapitalRequiredforBaselIII"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_CommonEquityTierOneCapitalRequiredforBaselIII_019e4c07-a6d2-74f7-9786-d836a0cc4496" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneRiskBasedCapitalRequiredforBaselIII_019e4c07-a6d2-7378-abb7-2ef34f6c504a" xlink:href="cubi-20260630.xsd#cubi_TierOneRiskBasedCapitalRequiredforBaselIII"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneRiskBasedCapitalRequiredforBaselIII_019e4c07-a6d2-7378-abb7-2ef34f6c504a" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CapitalRequiredforBaselIII_019e4c07-a6d2-7e0d-ac1a-0b8c3d2d4493" xlink:href="cubi-20260630.xsd#cubi_CapitalRequiredforBaselIII"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_CapitalRequiredforBaselIII_019e4c07-a6d2-7e0d-ac1a-0b8c3d2d4493" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneLeverageCapitalRequiredforBaselIII_019e4c07-a6d2-76a5-8038-8c8e744474a9" xlink:href="cubi-20260630.xsd#cubi_TierOneLeverageCapitalRequiredforBaselIII"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneLeverageCapitalRequiredforBaselIII_019e4c07-a6d2-76a5-8038-8c8e744474a9" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneCommonCapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-799c-b852-f011e137e904" xlink:href="cubi-20260630.xsd#cubi_TierOneCommonCapitalRequiredforBaselIIItoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneCommonCapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-799c-b852-f011e137e904" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneRiskBasedCapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-7a3a-9b4b-d9f9e33b9464" xlink:href="cubi-20260630.xsd#cubi_TierOneRiskBasedCapitalRequiredforBaselIIItoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneRiskBasedCapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-7a3a-9b4b-d9f9e33b9464" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-7cfe-aa1d-06988f787070" xlink:href="cubi-20260630.xsd#cubi_CapitalRequiredforBaselIIItoRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_CapitalRequiredforBaselIIItoRiskWeightedAssets_019e4c07-a6d2-7cfe-aa1d-06988f787070" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_TierOneLeverageCapitalRequiredforBaselIIItoAverageAssets_019e4c07-a6d2-7b1a-926a-47d52b90d135" xlink:href="cubi-20260630.xsd#cubi_TierOneLeverageCapitalRequiredforBaselIIItoAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_019e4c07-a6d2-77cb-92a3-0ef91670f00f" xlink:to="loc_cubi_TierOneLeverageCapitalRequiredforBaselIIItoAverageAssets_019e4c07-a6d2-7b1a-926a-47d52b90d135" xlink:type="arc" order="31"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSEstimatedFairValuesofFinancialInstrumentsDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSEstimatedFairValuesofFinancialInstrumentsDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSEstimatedFairValuesofFinancialInstrumentsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e4c07-a6d2-7f5c-bc39-5302da40a355" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7d08-8b36-bc18847cc2f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e4c07-a6d2-7f5c-bc39-5302da40a355" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7d08-8b36-bc18847cc2f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-7978-bbca-914bb3cece5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7d08-8b36-bc18847cc2f6" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-7978-bbca-914bb3cece5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7978-bbca-914bb3cece5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-7978-bbca-914bb3cece5c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7978-bbca-914bb3cece5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-743a-b674-8015a95d66e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-7978-bbca-914bb3cece5c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-743a-b674-8015a95d66e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e4c07-a6d2-7be3-950c-fb6d0d364399" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-743a-b674-8015a95d66e5" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e4c07-a6d2-7be3-950c-fb6d0d364399" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e4c07-a6d2-7d7b-be62-5b771f6c0f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-743a-b674-8015a95d66e5" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e4c07-a6d2-7d7b-be62-5b771f6c0f1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-739c-85fd-72500f4d2078" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-743a-b674-8015a95d66e5" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-739c-85fd-72500f4d2078" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e4c07-a6d2-7f5c-bc39-5302da40a355" xlink:to="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e4c07-a6d2-734f-8947-c0cffad189c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e4c07-a6d2-734f-8947-c0cffad189c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e4c07-a6d2-74e8-a5af-321d702a0d8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e4c07-a6d2-74e8-a5af-321d702a0d8b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-7a46-b694-cf8b7eb03662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-7a46-b694-cf8b7eb03662" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a6d2-7b1c-9752-4073e198f090" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a6d2-7b1c-9752-4073e198f090" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019e4c07-a6d2-7174-9606-50bffd761b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019e4c07-a6d2-7174-9606-50bffd761b6c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroup_019e4c07-a6d2-7849-b27b-0149c240175f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroup"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroup_019e4c07-a6d2-7849-b27b-0149c240175f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a6d2-7416-9326-de8cb90c2cf8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_019e4c07-a6d2-7416-9326-de8cb90c2cf8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_019e4c07-a6d2-77df-a3c9-35eccf1e3a66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_019e4c07-a6d2-77df-a3c9-35eccf1e3a66" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock_019e4c07-a6d2-7ed3-8376-281c85d31dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock_019e4c07-a6d2-7ed3-8376-281c85d31dc3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FederalHomeLoanBankStockAndFederalReserveBankStockFairValue_019e4c07-a6d2-76d7-8636-664dedd7b58a" xlink:href="cubi-20260630.xsd#cubi_FederalHomeLoanBankStockAndFederalReserveBankStockFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_cubi_FederalHomeLoanBankStockAndFederalReserveBankStockFairValue_019e4c07-a6d2-76d7-8636-664dedd7b58a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e4c07-a6d2-7cdc-aea8-cd202e1eeb12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e4c07-a6d2-780e-bfab-3ede052ed552" xlink:to="loc_us-gaap_DerivativeAssets_019e4c07-a6d2-7cdc-aea8-cd202e1eeb12" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e4c07-a6d2-7f5c-bc39-5302da40a355" xlink:to="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Deposits_019e4c07-a6d2-78eb-8e61-642232cf074a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Deposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_Deposits_019e4c07-a6d2-78eb-8e61-642232cf074a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsFairValueDisclosure_019e4c07-a6d2-7b9c-abe3-46e24eab9586" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_DepositsFairValueDisclosure_019e4c07-a6d2-7b9c-abe3-46e24eab9586" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch_019e4c07-a6d2-7eaa-9d08-97f534ff51e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch_019e4c07-a6d2-7eaa-9d08-97f534ff51e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure_019e4c07-a6d2-7c0e-af9e-023c47b5376c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure_019e4c07-a6d2-7c0e-af9e-023c47b5376c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherBorrowings_019e4c07-a6d2-778c-a94f-86e396104bf0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_OtherBorrowings_019e4c07-a6d2-778c-a94f-86e396104bf0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_BorrowingsFairValueDisclosure_019e4c07-a6d2-74f0-8c24-a0d28607f81f" xlink:href="cubi-20260630.xsd#cubi_BorrowingsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_cubi_BorrowingsFairValueDisclosure_019e4c07-a6d2-74f0-8c24-a0d28607f81f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_019e4c07-a6d2-7095-bdbe-a88aa06d3588" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubordinatedDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_SubordinatedDebt_019e4c07-a6d2-7095-bdbe-a88aa06d3588" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_SubordinatedDebtFairValueDisclosure_019e4c07-a6d2-73ac-a487-a23036ced383" xlink:href="cubi-20260630.xsd#cubi_SubordinatedDebtFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_cubi_SubordinatedDebtFairValueDisclosure_019e4c07-a6d2-73ac-a487-a23036ced383" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e4c07-a6d2-7dc9-ba0c-0cf3e17007db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_019e4c07-a6d2-7888-aada-19356564b042" xlink:to="loc_us-gaap_DerivativeLiabilities_019e4c07-a6d2-7dc9-ba0c-0cf3e17007db" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueonaRecurringandNonrecurringBasisDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueonaRecurringandNonrecurringBasisDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueonaRecurringandNonrecurringBasisDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-71e5-af25-d9ace90c2ae9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-71e5-af25-d9ace90c2ae9" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-74a4-aab6-789724752cdb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-74a4-aab6-789724752cdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-74a4-aab6-789724752cdb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-74a4-aab6-789724752cdb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-74a4-aab6-789724752cdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7a2f-bb0f-ed99bc6ccaba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-74a4-aab6-789724752cdb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7a2f-bb0f-ed99bc6ccaba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e4c07-a6d2-7864-a043-25db5c124dda" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7a2f-bb0f-ed99bc6ccaba" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e4c07-a6d2-7864-a043-25db5c124dda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e4c07-a6d2-7245-9dd1-e7548b661083" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7a2f-bb0f-ed99bc6ccaba" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e4c07-a6d2-7245-9dd1-e7548b661083" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-7ae9-9f44-30efec630dea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7a2f-bb0f-ed99bc6ccaba" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-7ae9-9f44-30efec630dea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-731b-9099-c32713c2b2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-731b-9099-c32713c2b2d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-731b-9099-c32713c2b2d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-731b-9099-c32713c2b2d9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-731b-9099-c32713c2b2d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-731b-9099-c32713c2b2d9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-7b54-9b57-63cc9addfd8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-7b54-9b57-63cc9addfd8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a6d2-71b2-bb09-2dcd37fe7400" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_019e4c07-a6d2-71b2-bb09-2dcd37fe7400" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a6d2-7dfc-ab71-ae019a281a7d" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_AgencyGuaranteedResidentialCollateralizedMortgageObligationsMember_019e4c07-a6d2-7dfc-ab71-ae019a281a7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a6d2-7400-853e-90e8de73ec0c" xlink:href="cubi-20260630.xsd#cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_AgencyGuaranteedCommercialCollateralizedMortgageObligationsMember_019e4c07-a6d2-7400-853e-90e8de73ec0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a6d2-7aa3-931d-83149cccb62d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e4c07-a6d2-7aa3-931d-83149cccb62d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a6d2-7e83-b69e-1ebe5768607f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_019e4c07-a6d2-7e83-b69e-1ebe5768607f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MortgageFinanceMember_019e4c07-a6d2-7f08-9dfe-f3510bc4b170" xlink:href="cubi-20260630.xsd#cubi_MortgageFinanceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_MortgageFinanceMember_019e4c07-a6d2-7f08-9dfe-f3510bc4b170" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InstallmentLoansMember_019e4c07-a6d2-70c7-a560-8e2f02a6bea7" xlink:href="cubi-20260630.xsd#cubi_InstallmentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_InstallmentLoansMember_019e4c07-a6d2-70c7-a560-8e2f02a6bea7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CollateralDependentLoansMember_019e4c07-a6d2-7050-b0ac-3e32d1f88db2" xlink:href="cubi-20260630.xsd#cubi_CollateralDependentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_CollateralDependentLoansMember_019e4c07-a6d2-7050-b0ac-3e32d1f88db2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherRealEstateOwnedMember_019e4c07-a6d2-7f5a-a703-f421cfa55f8a" xlink:href="cubi-20260630.xsd#cubi_OtherRealEstateOwnedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7d91-88fa-02e12174bbfc" xlink:to="loc_cubi_OtherRealEstateOwnedMember_019e4c07-a6d2-7f5a-a703-f421cfa55f8a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7699-9b61-21eafe8f78f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7699-9b61-21eafe8f78f3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7699-9b61-21eafe8f78f3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7699-9b61-21eafe8f78f3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7699-9b61-21eafe8f78f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7da8-a170-53e7583da07d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7699-9b61-21eafe8f78f3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7da8-a170-53e7583da07d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-757f-bd47-9bdf0e5514d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7da8-a170-53e7583da07d" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-757f-bd47-9bdf0e5514d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_019e4c07-a6d2-7082-a2a0-395e220328fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7da8-a170-53e7583da07d" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_019e4c07-a6d2-7082-a2a0-395e220328fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e4c07-a6d2-7c3d-99ab-f66aaf75e780" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:to="loc_srt_RangeAxis_019e4c07-a6d2-7c3d-99ab-f66aaf75e780" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7c3d-99ab-f66aaf75e780_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7c3d-99ab-f66aaf75e780" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7c3d-99ab-f66aaf75e780_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7d95-b22d-3cf9cf2dbd6a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7c3d-99ab-f66aaf75e780" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7d95-b22d-3cf9cf2dbd6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_019e4c07-a6d2-7b7e-a858-ebb4133be6eb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-7d95-b22d-3cf9cf2dbd6a" xlink:to="loc_srt_WeightedAverageMember_019e4c07-a6d2-7b7e-a858-ebb4133be6eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e4c07-a6d2-7675-bd77-982bc8bf63cc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-7d95-b22d-3cf9cf2dbd6a" xlink:to="loc_srt_MinimumMember_019e4c07-a6d2-7675-bd77-982bc8bf63cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e4c07-a6d2-78eb-b1d4-63bc6b8d3d64" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-7d95-b22d-3cf9cf2dbd6a" xlink:to="loc_srt_MaximumMember_019e4c07-a6d2-78eb-b1d4-63bc6b8d3d64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-711e-b086-faaef65ca1fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7ffc-907c-d5a07fb4420c" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-711e-b086-faaef65ca1fd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-711e-b086-faaef65ca1fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-711e-b086-faaef65ca1fd" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-711e-b086-faaef65ca1fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-706d-8b9f-c1a6cb3a0f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-711e-b086-faaef65ca1fd" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-706d-8b9f-c1a6cb3a0f0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MeasurementInputLiquidationExpensesMember_019e4c07-a6d2-7eae-b9ed-89982ba82077" xlink:href="cubi-20260630.xsd#cubi_MeasurementInputLiquidationExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-706d-8b9f-c1a6cb3a0f0b" xlink:to="loc_cubi_MeasurementInputLiquidationExpensesMember_019e4c07-a6d2-7eae-b9ed-89982ba82077" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-71e5-af25-d9ace90c2ae9" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-7341-b84f-b343fea12fbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-7341-b84f-b343fea12fbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e4c07-a6d2-70e7-b276-a54eefe126bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:to="loc_us-gaap_DerivativeAssets_019e4c07-a6d2-70e7-b276-a54eefe126bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_019e4c07-a6d2-7113-b9b2-ca7f81ec3065" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansHeldForSaleFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:to="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_019e4c07-a6d2-7113-b9b2-ca7f81ec3065" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_019e4c07-a6d2-7474-8341-5d6af567199d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_019e4c07-a6d2-7474-8341-5d6af567199d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019e4c07-a6d2-78bf-9e1e-459107b51832" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e4c07-a6d2-74a5-a1b2-39369db12327" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019e4c07-a6d2-78bf-9e1e-459107b51832" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e4c07-a6d2-735e-b2f9-767bc56bb1af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-71e5-af25-d9ace90c2ae9" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e4c07-a6d2-735e-b2f9-767bc56bb1af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e4c07-a6d2-759e-bfca-cf0dc622dcca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e4c07-a6d2-735e-b2f9-767bc56bb1af" xlink:to="loc_us-gaap_DerivativeLiabilities_019e4c07-a6d2-759e-bfca-cf0dc622dcca" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7b1a-9881-f37a88d95ae9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-74a4-98d4-ec0543433d4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7b1a-9881-f37a88d95ae9" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-74a4-98d4-ec0543433d4f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7f1d-9805-8665c5872b6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-74a4-98d4-ec0543433d4f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7f1d-9805-8665c5872b6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7f1d-9805-8665c5872b6f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7f1d-9805-8665c5872b6f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7f1d-9805-8665c5872b6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-748b-9a51-98050baeb8ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7f1d-9805-8665c5872b6f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-748b-9a51-98050baeb8ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-713d-bf18-906ca4e5095e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-748b-9a51-98050baeb8ba" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-713d-bf18-906ca4e5095e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7c6e-815e-2366195ad9d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-74a4-98d4-ec0543433d4f" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7c6e-815e-2366195ad9d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7c6e-815e-2366195ad9d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7c6e-815e-2366195ad9d2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7c6e-815e-2366195ad9d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7835-a52e-038dd9c6c5d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7c6e-815e-2366195ad9d2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7835-a52e-038dd9c6c5d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-758f-9c3a-60f4e0b67262" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7835-a52e-038dd9c6c5d6" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-758f-9c3a-60f4e0b67262" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7b1a-9881-f37a88d95ae9" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-7e62-b09a-0bed45caafc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-7e62-b09a-0bed45caafc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e4c07-a6d2-7f98-adba-74b494e58818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e4c07-a6d2-7f98-adba-74b494e58818" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPrincipalPaymentsAndPremiumAmortization_019e4c07-a6d2-7722-b392-bee0695c2068" xlink:href="cubi-20260630.xsd#cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPrincipalPaymentsAndPremiumAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPrincipalPaymentsAndPremiumAmortization_019e4c07-a6d2-7722-b392-bee0695c2068" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIncreaseInAllowanceForCreditLosses_019e4c07-a6d2-7252-9ec0-0e2d2d2540bb" xlink:href="cubi-20260630.xsd#cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIncreaseInAllowanceForCreditLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIncreaseInAllowanceForCreditLosses_019e4c07-a6d2-7252-9ec0-0e2d2d2540bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDecreaseInAllowanceForCreditLosses_019e4c07-a6d2-773a-9d62-68447224de07" xlink:href="cubi-20260630.xsd#cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDecreaseInAllowanceForCreditLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_cubi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDecreaseInAllowanceForCreditLosses_019e4c07-a6d2-773a-9d62-68447224de07" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e4c07-a6d2-7fa9-929d-c2d65d10eeed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-725c-887f-aad89f24ee0f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e4c07-a6d2-7fa9-929d-c2d65d10eeed" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-7ecd-86de-c861b2d27563" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSStatementofChangesinLevel3AssetsMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7adb-a826-266002e4c87f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7bb0-927c-fbbbdbfc0f36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7adb-a826-266002e4c87f" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7bb0-927c-fbbbdbfc0f36" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7bfa-a165-d4bbe7510986" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7bb0-927c-fbbbdbfc0f36" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7bfa-a165-d4bbe7510986" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7bfa-a165-d4bbe7510986_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7bfa-a165-d4bbe7510986" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7bfa-a165-d4bbe7510986_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7828-81cd-9b30db16f4da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e4c07-a6d2-7bfa-a165-d4bbe7510986" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7828-81cd-9b30db16f4da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-73f0-9e2e-aa04341f06e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e4c07-a6d2-7828-81cd-9b30db16f4da" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e4c07-a6d2-73f0-9e2e-aa04341f06e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7468-bb19-b11b7c968792" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7bb0-927c-fbbbdbfc0f36" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7468-bb19-b11b7c968792" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7468-bb19-b11b7c968792_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7468-bb19-b11b7c968792" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7468-bb19-b11b7c968792_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7f58-b9aa-249ba213a865" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7468-bb19-b11b7c968792" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7f58-b9aa-249ba213a865" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherInstallmentLoansMember_019e4c07-a6d2-71fa-84a4-59ab45604fc0" xlink:href="cubi-20260630.xsd#cubi_OtherInstallmentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7f58-b9aa-249ba213a865" xlink:to="loc_cubi_OtherInstallmentLoansMember_019e4c07-a6d2-71fa-84a4-59ab45604fc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-7adb-a826-266002e4c87f" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-7238-8c11-da07147a0e7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-7238-8c11-da07147a0e7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_019e4c07-a6d2-78e9-8008-7f68a5016692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_019e4c07-a6d2-78e9-8008-7f68a5016692" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales_019e4c07-a6d2-7d9d-a421-507beb7c274b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales_019e4c07-a6d2-7d9d-a421-507beb7c274b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e4c07-a6d2-7c33-974e-be1c9948adef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e4c07-a6d2-7c33-974e-be1c9948adef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e4c07-a6d2-71e9-af19-3fc6e928f569" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e4c07-a6d2-7544-8e6e-0c962597b65b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e4c07-a6d2-71e9-af19-3fc6e928f569" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019e4c07-a6d2-74b9-835b-e03e8671b0f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandFinancialLiabilitiesMeasuredatFairValueonRecurringandNonrecurringBasisDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandFinancialLiabilitiesMeasuredatFairValueonRecurringandNonrecurringBasisDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DISCLOSURESABOUTFAIRVALUEOFFINANCIALINSTRUMENTSSummaryofFinancialAssetsandFinancialLiabilitiesMeasuredatFairValueonRecurringandNonrecurringBasisDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_srt_RangeAxis_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e4c07-a6d2-77e6-8b59-217a357db03e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e4c07-a6d2-7942-a2e6-b73e7ef31ca8" xlink:to="loc_srt_RangeMember_019e4c07-a6d2-77e6-8b59-217a357db03e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e4c07-a6d2-7deb-b1d3-e4f150656bd6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-77e6-8b59-217a357db03e" xlink:to="loc_srt_MinimumMember_019e4c07-a6d2-7deb-b1d3-e4f150656bd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e4c07-a6d2-7a65-84e9-734ff9abba8c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-77e6-8b59-217a357db03e" xlink:to="loc_srt_MaximumMember_019e4c07-a6d2-7a65-84e9-734ff9abba8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_019e4c07-a6d2-755a-aab0-54b3451cc2f6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e4c07-a6d2-77e6-8b59-217a357db03e" xlink:to="loc_srt_WeightedAverageMember_019e4c07-a6d2-755a-aab0-54b3451cc2f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7c6d-887a-20ffda104672" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7c6d-887a-20ffda104672" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7c6d-887a-20ffda104672_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7c6d-887a-20ffda104672" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-7c6d-887a-20ffda104672_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-74d7-ac7f-c05a84d3cb2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e4c07-a6d2-7c6d-887a-20ffda104672" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-74d7-ac7f-c05a84d3cb2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-7580-9977-229ba581c9be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-74d7-ac7f-c05a84d3cb2b" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019e4c07-a6d2-7580-9977-229ba581c9be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherRealEstateOwnedMember_019e4c07-a6d2-7a50-a5cd-0b310e1d3d32" xlink:href="cubi-20260630.xsd#cubi_OtherRealEstateOwnedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e4c07-a6d2-74d7-ac7f-c05a84d3cb2b" xlink:to="loc_cubi_OtherRealEstateOwnedMember_019e4c07-a6d2-7a50-a5cd-0b310e1d3d32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-741c-93ce-3cfee99e2043" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-741c-93ce-3cfee99e2043" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-741c-93ce-3cfee99e2043_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-741c-93ce-3cfee99e2043" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-741c-93ce-3cfee99e2043_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7f39-a703-bcb3461cd575" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e4c07-a6d2-741c-93ce-3cfee99e2043" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7f39-a703-bcb3461cd575" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-757c-ada8-62b40a7643e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e4c07-a6d2-7f39-a703-bcb3461cd575" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e4c07-a6d2-757c-ada8-62b40a7643e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-7c29-9433-298088905f3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-7c29-9433-298088905f3b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7c29-9433-298088905f3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-7c29-9433-298088905f3b" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7c29-9433-298088905f3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e4c07-a6d2-7c29-9433-298088905f3b" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_019e4c07-a6d2-74f4-86fe-2afc4e4a3ecb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_019e4c07-a6d2-74f4-86fe-2afc4e4a3ecb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MeasurementInputAnnualizedLossRateMember_019e4c07-a6d2-7707-9fbb-62cda800fae9" xlink:href="cubi-20260630.xsd#cubi_MeasurementInputAnnualizedLossRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:to="loc_cubi_MeasurementInputAnnualizedLossRateMember_019e4c07-a6d2-7707-9fbb-62cda800fae9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPrepaymentRateMember_019e4c07-a6d2-730e-95cf-3923ed2b0a16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPrepaymentRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:to="loc_us-gaap_MeasurementInputPrepaymentRateMember_019e4c07-a6d2-730e-95cf-3923ed2b0a16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_MeasurementInputLiquidationExpensesMember_019e4c07-a6d2-75ce-acf3-3f952b3b02d6" xlink:href="cubi-20260630.xsd#cubi_MeasurementInputLiquidationExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e4c07-a6d2-7a83-bf67-9079f09adaf1" xlink:to="loc_cubi_MeasurementInputLiquidationExpensesMember_019e4c07-a6d2-75ce-acf3-3f952b3b02d6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019e4c07-a6d2-7e36-bd10-a92308054f9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019e4c07-a6d2-7e36-bd10-a92308054f9f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e4c07-a6d2-7e36-bd10-a92308054f9f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e4c07-a6d2-7e36-bd10-a92308054f9f" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e4c07-a6d2-7e36-bd10-a92308054f9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e4c07-a6d2-7d20-8d66-575e42f5d058" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e4c07-a6d2-7e36-bd10-a92308054f9f" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e4c07-a6d2-7d20-8d66-575e42f5d058" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e4c07-a6d2-743d-8765-bf402be1ea56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e4c07-a6d2-7d20-8d66-575e42f5d058" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e4c07-a6d2-743d-8765-bf402be1ea56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e4c07-a6d2-7945-9b50-4a25eb0a5ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e4c07-a6d2-743d-8765-bf402be1ea56" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e4c07-a6d2-7945-9b50-4a25eb0a5ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_019e4c07-a6d2-702e-9edb-d32b825198d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e4c07-a6d2-7407-a174-3d18f00f90c0" xlink:to="loc_us-gaap_ValuationTechniqueAxis_019e4c07-a6d2-702e-9edb-d32b825198d8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_019e4c07-a6d2-702e-9edb-d32b825198d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_019e4c07-a6d2-702e-9edb-d32b825198d8" xlink:to="loc_us-gaap_ValuationTechniqueDomain_019e4c07-a6d2-702e-9edb-d32b825198d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_019e4c07-a6d2-72fb-beba-ef60762cb33a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_019e4c07-a6d2-702e-9edb-d32b825198d8" xlink:to="loc_us-gaap_ValuationTechniqueDomain_019e4c07-a6d2-72fb-beba-ef60762cb33a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CollateralAppraisalMember_019e4c07-a6d2-78b4-add5-3026a3b66cf5" xlink:href="cubi-20260630.xsd#cubi_CollateralAppraisalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_019e4c07-a6d2-72fb-beba-ef60762cb33a" xlink:to="loc_cubi_CollateralAppraisalMember_019e4c07-a6d2-78b4-add5-3026a3b66cf5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-73ef-8f28-a6989956db6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019e4c07-a6d2-73ef-8f28-a6989956db6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRealEstateAndForeclosedAssets_019e4c07-a6d2-770c-9112-7c90893c9d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherRealEstateAndForeclosedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:to="loc_us-gaap_OtherRealEstateAndForeclosedAssets_019e4c07-a6d2-770c-9112-7c90893c9d1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_019e4c07-a6d2-748e-b752-7f8c9fde9983" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_019e4c07-a6d2-748e-b752-7f8c9fde9983" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OtherRealEstateOwnedMeasurementInputs_019e4c07-a6d2-7749-8565-7caf7d353b82" xlink:href="cubi-20260630.xsd#cubi_OtherRealEstateOwnedMeasurementInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e4c07-a6d2-70c9-a0b8-85ea863844a7" xlink:to="loc_cubi_OtherRealEstateOwnedMeasurementInputs_019e4c07-a6d2-7749-8565-7caf7d353b82" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESAdditionalInformationDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-7b91-8015-8502fdd524c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-7b91-8015-8502fdd524c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7b91-8015-8502fdd524c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-7b91-8015-8502fdd524c9" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7b91-8015-8502fdd524c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7716-bd05-5ce5f64139fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-7b91-8015-8502fdd524c9" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7716-bd05-5ce5f64139fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019e4c07-a6d2-7b53-94fe-550129a6fad5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7716-bd05-5ce5f64139fe" xlink:to="loc_us-gaap_CashFlowHedgingMember_019e4c07-a6d2-7b53-94fe-550129a6fad5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueHedgingMember_019e4c07-a6d2-7b5b-ad1c-2d2416dd0419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-7716-bd05-5ce5f64139fe" xlink:to="loc_us-gaap_FairValueHedgingMember_019e4c07-a6d2-7b5b-ad1c-2d2416dd0419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-79a0-80e2-da4503fd8461" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-79a0-80e2-da4503fd8461" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-79a0-80e2-da4503fd8461_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-79a0-80e2-da4503fd8461" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-79a0-80e2-da4503fd8461_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7e7b-99f9-0e5d95ba7efa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-79a0-80e2-da4503fd8461" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7e7b-99f9-0e5d95ba7efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e4c07-a6d2-741d-a8cb-8e124ab4fc55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7e7b-99f9-0e5d95ba7efa" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e4c07-a6d2-741d-a8cb-8e124ab4fc55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7810-8d01-e5d63fcb1ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7e7b-99f9-0e5d95ba7efa" xlink:to="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7810-8d01-e5d63fcb1ce4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7857-a362-406f52bafcb2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7857-a362-406f52bafcb2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7857-a362-406f52bafcb2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7857-a362-406f52bafcb2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7857-a362-406f52bafcb2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7857-a362-406f52bafcb2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-73f6-be35-85084afab8a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:to="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-73f6-be35-85084afab8a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7c59-8023-a182c0aefe1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:to="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7c59-8023-a182c0aefe1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_019e4c07-a6d2-735e-baf3-24e9f05abab4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:to="loc_us-gaap_InterestRateCapMember_019e4c07-a6d2-735e-baf3-24e9f05abab4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditRiskContractMember_019fb3b1-0432-7a02-bb6e-5efad4efa148" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditRiskContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a96-80b1-2a9349b08eb6" xlink:to="loc_us-gaap_CreditRiskContractMember_019fb3b1-0432-7a02-bb6e-5efad4efa148" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-7c2f-b3cd-e52a6025b154" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-7c2f-b3cd-e52a6025b154" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7c2f-b3cd-e52a6025b154_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-7c2f-b3cd-e52a6025b154" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-7c2f-b3cd-e52a6025b154_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-77c3-8f7d-69c07a147b6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e4c07-a6d2-7c2f-b3cd-e52a6025b154" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-77c3-8f7d-69c07a147b6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7eeb-9a54-56fab5fe5224" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e4c07-a6d2-77c3-8f7d-69c07a147b6a" xlink:to="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7eeb-9a54-56fab5fe5224" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019fb397-247a-7b1d-acb4-c6ca0a10656b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-74e6-86ab-679af4aa1b11" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019fb397-247a-7b1d-acb4-c6ca0a10656b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019fb397-247a-7b1d-acb4-c6ca0a10656b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019fb397-247a-7b1d-acb4-c6ca0a10656b" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019fb397-247a-7b1d-acb4-c6ca0a10656b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019fb397-247a-75a0-9574-346cad3f57d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_019fb397-247a-7b1d-acb4-c6ca0a10656b" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019fb397-247a-75a0-9574-346cad3f57d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_CommercialandIndustrialMember_019fb397-3f5e-78a3-bfd8-298b1ea270ba" xlink:href="cubi-20260630.xsd#cubi_CommercialandIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_019fb397-247a-75a0-9574-346cad3f57d8" xlink:to="loc_cubi_CommercialandIndustrialMember_019fb397-3f5e-78a3-bfd8-298b1ea270ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019e4c07-a6d2-7b67-bdc3-2b4117e06b63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019e4c07-a6d2-7b67-bdc3-2b4117e06b63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e4c07-a6d2-73ff-ad92-37261f4480f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e4c07-a6d2-73ff-ad92-37261f4480f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DerivativeNumberOfInstrumentsEnteredInto_019e4c07-a6d2-7ee8-b093-46afe93b16b6" xlink:href="cubi-20260630.xsd#cubi_DerivativeNumberOfInstrumentsEnteredInto"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_cubi_DerivativeNumberOfInstrumentsEnteredInto_019e4c07-a6d2-7ee8-b093-46afe93b16b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_019e4c07-a6d2-7481-84cb-2717ba0d8548" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_019e4c07-a6d2-7481-84cb-2717ba0d8548" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019e4c07-a6d2-747d-82e5-d0d8c6019cc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DebtInstrumentTerm_019e4c07-a6d2-747d-82e5-d0d8c6019cc2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfInterestRateDerivativesHeld_019e4c07-a6d2-7980-a68b-4efb4bef6a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfInterestRateDerivativesHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_NumberOfInterestRateDerivativesHeld_019e4c07-a6d2-7980-a68b-4efb4bef6a5a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_NotionalAmountOfInterestRateDerivativesEnteredIntoDuringThePeriod_019ed1da-976c-7d7d-8c3c-b4b1ff1c5ae4" xlink:href="cubi-20260630.xsd#cubi_NotionalAmountOfInterestRateDerivativesEnteredIntoDuringThePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_cubi_NotionalAmountOfInterestRateDerivativesEnteredIntoDuringThePeriod_019ed1da-976c-7d7d-8c3c-b4b1ff1c5ae4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_NumberOfInterestRateDerivativesEnteredIntoDuringThePeriod_019e4c07-a6d2-7dc1-a587-5dbd20e749df" xlink:href="cubi-20260630.xsd#cubi_NumberOfInterestRateDerivativesEnteredIntoDuringThePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_cubi_NumberOfInterestRateDerivativesEnteredIntoDuringThePeriod_019e4c07-a6d2-7dc1-a587-5dbd20e749df" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DerivativeNotionalAmountAdditions_019e4c07-a6d2-7559-a79b-49ba990ae068" xlink:href="cubi-20260630.xsd#cubi_DerivativeNotionalAmountAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_cubi_DerivativeNotionalAmountAdditions_019e4c07-a6d2-7559-a79b-49ba990ae068" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019fb3aa-52e7-79f4-86d6-e1ff848a1235" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeAssets_019fb3aa-52e7-79f4-86d6-e1ff848a1235" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019fb3aa-52e7-77ef-b864-c7ea105bc800" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeLiabilities_019fb3aa-52e7-77ef-b864-c7ea105bc800" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DerivativeNetAssetPositionAggregateFairValue_019e4c07-a6d2-7b5e-9c1d-b364f70e46ff" xlink:href="cubi-20260630.xsd#cubi_DerivativeNetAssetPositionAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_cubi_DerivativeNetAssetPositionAggregateFairValue_019e4c07-a6d2-7b5e-9c1d-b364f70e46ff" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueOfCollateral_019e4c07-a6d2-7380-8447-955e375ae999" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueOfCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeAssetFairValueOfCollateral_019e4c07-a6d2-7380-8447-955e375ae999" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_019fb3a7-2016-72a8-8c93-774422cf4fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollateralAlreadyPostedAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_019fb3a7-2016-72a8-8c93-774422cf4fb7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueAmountOffsetAgainstCollateralNet_019fb3a7-2016-799c-8931-961ec6c3892e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueAmountOffsetAgainstCollateralNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7800-b0d1-56a89087292f" xlink:to="loc_us-gaap_DerivativeFairValueAmountOffsetAgainstCollateralNet_019fb3a7-2016-799c-8931-961ec6c3892e" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESCumulativeBasisAdjustmentforFairValueHedgesDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESCumulativeBasisAdjustmentforFairValueHedgesDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESCumulativeBasisAdjustmentforFairValueHedgesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-74dc-a613-4db160af6928" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-7711-a3db-15a00644235b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-74dc-a613-4db160af6928" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-7711-a3db-15a00644235b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e4c07-a6d2-7d8a-9269-86818ee5ad0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-7711-a3db-15a00644235b" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e4c07-a6d2-7d8a-9269-86818ee5ad0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-7d8a-9269-86818ee5ad0d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e4c07-a6d2-7d8a-9269-86818ee5ad0d" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-7d8a-9269-86818ee5ad0d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-77f2-a44c-8255c09883a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e4c07-a6d2-7d8a-9269-86818ee5ad0d" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-77f2-a44c-8255c09883a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsMember_019e4c07-a6d2-7443-85d9-64a6e809bccc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-77f2-a44c-8255c09883a3" xlink:to="loc_us-gaap_DepositsMember_019e4c07-a6d2-7443-85d9-64a6e809bccc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7a0d-b5c2-050022794a6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e4c07-a6d2-77f2-a44c-8255c09883a3" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7a0d-b5c2-050022794a6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgedAssetFairValueHedge_019e4c07-a6d2-72fb-aea1-4163bb94f4f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgedAssetFairValueHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-74dc-a613-4db160af6928" xlink:to="loc_us-gaap_HedgedAssetFairValueHedge_019e4c07-a6d2-72fb-aea1-4163bb94f4f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease_019e4c07-a6d2-79fd-b924-420ec56b5201" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-74dc-a613-4db160af6928" xlink:to="loc_us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease_019e4c07-a6d2-79fd-b924-420ec56b5201" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e4c07-a6d2-73da-bafa-94ee15050c12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e4c07-a6d2-73da-bafa-94ee15050c12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-798a-9917-0f5729c7306d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-798a-9917-0f5729c7306d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7856-8dd3-e95682fd5d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:to="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7856-8dd3-e95682fd5d8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7062-9030-665199c912e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7062-9030-665199c912e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateSwapsCapsAndCollarsMember_019e4c07-a6d2-7b24-b3c8-94deefdc4080" xlink:href="cubi-20260630.xsd#cubi_InterestRateSwapsCapsAndCollarsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:to="loc_cubi_InterestRateSwapsCapsAndCollarsMember_019e4c07-a6d2-7b24-b3c8-94deefdc4080" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7853-9d2e-e1320dbfc9e8" xlink:href="cubi-20260630.xsd#cubi_InterestRateSwapsAndCapsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:to="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7853-9d2e-e1320dbfc9e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7fa0-a5f9-865d03baac4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7fa0-a5f9-865d03baac4f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-7a9b-9ed1-5b03fff66cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-7a9b-9ed1-5b03fff66cf6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail_1" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail_1"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESFairValueofDerivativeFinancialInstrumentsDetail_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-798a-9917-0f5729c7306d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-798a-9917-0f5729c7306d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-798a-9917-0f5729c7306d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7856-8dd3-e95682fd5d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-709e-84bd-3fe55ec78711" xlink:to="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7856-8dd3-e95682fd5d8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7d9c-99f7-175aa6b9b072" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7062-9030-665199c912e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7062-9030-665199c912e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7062-9030-665199c912e9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateSwapsCapsAndCollarsMember_019e4c07-a6d2-7b24-b3c8-94deefdc4080" xlink:href="cubi-20260630.xsd#cubi_InterestRateSwapsCapsAndCollarsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:to="loc_cubi_InterestRateSwapsCapsAndCollarsMember_019e4c07-a6d2-7b24-b3c8-94deefdc4080" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7853-9d2e-e1320dbfc9e8" xlink:href="cubi-20260630.xsd#cubi_InterestRateSwapsAndCapsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7a60-a1af-3ebdfb20f0ea" xlink:to="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7853-9d2e-e1320dbfc9e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7fa0-a5f9-865d03baac4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7fa0-a5f9-865d03baac4f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-7a9b-9ed1-5b03fff66cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7ec8-88a9-01ff393a5699" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-7a9b-9ed1-5b03fff66cf6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESEffectofDerivativeFinancialInstrumentsonNetIncomeandComprehensiveIncomeDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESEffectofDerivativeFinancialInstrumentsonNetIncomeandComprehensiveIncomeDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESEffectofDerivativeFinancialInstrumentsonNetIncomeandComprehensiveIncomeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7304-adef-103f66e0d5c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7a98-887a-a8bcd15b78b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7304-adef-103f66e0d5c0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7a98-887a-a8bcd15b78b1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-7c78-ba43-447bab17643d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7a98-887a-a8bcd15b78b1" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-7c78-ba43-447bab17643d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7c78-ba43-447bab17643d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-7c78-ba43-447bab17643d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7c78-ba43-447bab17643d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7f22-9027-398a6614c018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e4c07-a6d2-7c78-ba43-447bab17643d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7f22-9027-398a6614c018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e4c07-a6d2-7a50-857e-9a23e0f5b8d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7f22-9027-398a6614c018" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e4c07-a6d2-7a50-857e-9a23e0f5b8d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7b76-affb-c114e10e9bdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e4c07-a6d2-7f22-9027-398a6614c018" xlink:to="loc_us-gaap_NondesignatedMember_019e4c07-a6d2-7b76-affb-c114e10e9bdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-741f-9305-2d9afb7a2a01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7a98-887a-a8bcd15b78b1" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-741f-9305-2d9afb7a2a01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-741f-9305-2d9afb7a2a01_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-741f-9305-2d9afb7a2a01" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-741f-9305-2d9afb7a2a01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-741f-9305-2d9afb7a2a01" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7da3-9e05-54769646079e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:to="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7da3-9e05-54769646079e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsMember_019e4c07-a6d2-7f8d-8a16-3d24836ed60a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:to="loc_us-gaap_DepositsMember_019e4c07-a6d2-7f8d-8a16-3d24836ed60a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7c8a-b29b-2215cb5a86bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMember_019e4c07-a6d2-7c8a-b29b-2215cb5a86bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7ed8-9491-daa51620df0b" xlink:href="cubi-20260630.xsd#cubi_InterestRateSwapsAndCapsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7412-b078-9a1f84c1ecf3" xlink:to="loc_cubi_InterestRateSwapsAndCapsMember_019e4c07-a6d2-7ed8-9491-daa51620df0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-77e2-a1e0-9ea4d366883e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e4c07-a6d2-7a98-887a-a8bcd15b78b1" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-77e2-a1e0-9ea4d366883e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-77e2-a1e0-9ea4d366883e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-77e2-a1e0-9ea4d366883e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-77e2-a1e0-9ea4d366883e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-763f-adc1-c16c444774ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e4c07-a6d2-77e2-a1e0-9ea4d366883e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-763f-adc1-c16c444774ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueHedgingMember_019e4c07-a6d2-7d28-8c43-e868f85ff2c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e4c07-a6d2-763f-adc1-c16c444774ec" xlink:to="loc_us-gaap_FairValueHedgingMember_019e4c07-a6d2-7d28-8c43-e868f85ff2c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019e4c07-a6d2-7129-86af-4a8a6599aa42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e4c07-a6d2-7304-adef-103f66e0d5c0" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019e4c07-a6d2-7129-86af-4a8a6599aa42" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74b8-873b-0b4758c25b39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74b8-873b-0b4758c25b39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7f8e-b037-f8d574b69df4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:to="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7f8e-b037-f8d574b69df4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e4c07-a6d2-71e0-8bfe-8fb57a691db9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e4c07-a6d2-71e0-8bfe-8fb57a691db9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019e4c07-a6d2-7be1-aae3-c834a02314ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019e4c07-a6d2-7be1-aae3-c834a02314ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019e4c07-a6d2-7d17-b8c6-c539b4b7576d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019e4c07-a6d2-7d17-b8c6-c539b4b7576d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails_1" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails_1"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESScheduleofEffectOfDerivativeInstrumentOnComprehensiveIncomeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e4c07-a6d2-79e0-b5ed-c2db4adb310d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74b8-873b-0b4758c25b39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74b8-873b-0b4758c25b39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-74b8-873b-0b4758c25b39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7f8e-b037-f8d574b69df4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7b43-beb3-468ac61f29d2" xlink:to="loc_us-gaap_InterestRateSwapMember_019e4c07-a6d2-7f8e-b037-f8d574b69df4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019e4c07-a6d2-7be1-aae3-c834a02314ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019e4c07-a6d2-7be1-aae3-c834a02314ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019e4c07-a6d2-7d17-b8c6-c539b4b7576d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e4c07-a6d2-73cc-b396-a7b641b4876e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019e4c07-a6d2-7d17-b8c6-c539b4b7576d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialAssetsandDerivativeAssetsDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialAssetsandDerivativeAssetsDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialAssetsandDerivativeAssetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingAssetsTable_019e4c07-a6d2-7a73-a42e-1c6115cd89c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:to="loc_us-gaap_OffsettingAssetsTable_019e4c07-a6d2-7a73-a42e-1c6115cd89c1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-770a-ac47-a8cdb66282d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OffsettingAssetsTable_019e4c07-a6d2-7a73-a42e-1c6115cd89c1" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-770a-ac47-a8cdb66282d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-770a-ac47-a8cdb66282d0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-770a-ac47-a8cdb66282d0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-770a-ac47-a8cdb66282d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7c54-9404-5bd5879dd12c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-770a-ac47-a8cdb66282d0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7c54-9404-5bd5879dd12c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-7962-b88e-56da2fba041f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7c54-9404-5bd5879dd12c" xlink:to="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-7962-b88e-56da2fba041f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7e57-8af0-07f9d45f029d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e4c07-a6d2-7e57-8af0-07f9d45f029d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction_019e4c07-a6d2-7a65-9883-fd87a2420ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:to="loc_us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction_019e4c07-a6d2-7a65-9883-fd87a2420ee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnCash_019e4c07-a6d2-7123-be55-74ce3f641818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnCash_019e4c07-a6d2-7123-be55-74ce3f641818" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019e4c07-a6d2-7130-9b07-c182a5faa039" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_019e4c07-a6d2-7174-bd5c-93ffb5c1a0b4" xlink:to="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019e4c07-a6d2-7130-9b07-c182a5faa039" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialLiabilitiesandDerivativeLiabilitiesDetail" xlink:type="simple" xlink:href="cubi-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialLiabilitiesandDerivativeLiabilitiesDetail"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGACTIVITIESSummaryofOffsettingofFinancialLiabilitiesandDerivativeLiabilitiesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingLiabilitiesTable_019e4c07-a6d2-7acb-849e-3573b33282a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:to="loc_us-gaap_OffsettingLiabilitiesTable_019e4c07-a6d2-7acb-849e-3573b33282a3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7741-8125-d59da3020378" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OffsettingLiabilitiesTable_019e4c07-a6d2-7acb-849e-3573b33282a3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7741-8125-d59da3020378" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7741-8125-d59da3020378_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7741-8125-d59da3020378" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-7741-8125-d59da3020378_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74a6-bdd8-b72f49e70fd6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e4c07-a6d2-7741-8125-d59da3020378" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74a6-bdd8-b72f49e70fd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-79ab-b2b7-1794ca820ff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e4c07-a6d2-74a6-bdd8-b72f49e70fd6" xlink:to="loc_us-gaap_InterestRateContractMember_019e4c07-a6d2-79ab-b2b7-1794ca820ff1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-704d-9a7e-aabcad946f4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e4c07-a6d2-704d-9a7e-aabcad946f4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction_019e4c07-a6d2-7976-ae8e-676bdefad92d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:to="loc_us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction_019e4c07-a6d2-7976-ae8e-676bdefad92d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimCash_019e4c07-a6d2-7bb6-8969-fde3a9364846" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimCash_019e4c07-a6d2-7bb6-8969-fde3a9364846" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019e4c07-a6d2-781c-bfc6-1724a27c17d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_019e4c07-a6d2-7b53-ba72-320bad6ac80e" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019e4c07-a6d2-781c-bfc6-1724a27c17d7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://customersbank.com/role/BUSINESSSEGMENTSDetails" xlink:type="simple" xlink:href="cubi-20260630.xsd#BUSINESSSEGMENTSDetails"/>
  <link:definitionLink xlink:role="http://customersbank.com/role/BUSINESSSEGMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e4c07-a6d2-74d5-ad49-da4987f2c544" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e4c07-a6d2-74d5-ad49-da4987f2c544" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e4c07-a6d2-7dea-b34f-6e531039e203" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e4c07-a6d2-74d5-ad49-da4987f2c544" xlink:to="loc_srt_ConsolidationItemsAxis_019e4c07-a6d2-7dea-b34f-6e531039e203" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7dea-b34f-6e531039e203_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e4c07-a6d2-7dea-b34f-6e531039e203" xlink:to="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7dea-b34f-6e531039e203_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7883-8156-c4eb8a66bbe8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e4c07-a6d2-7dea-b34f-6e531039e203" xlink:to="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7883-8156-c4eb8a66bbe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019e4c07-a6d2-7a04-908f-26990664abc8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7883-8156-c4eb8a66bbe8" xlink:to="loc_us-gaap_OperatingSegmentsMember_019e4c07-a6d2-7a04-908f-26990664abc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_019e4c07-a6d2-78da-ad92-fa649500043f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e4c07-a6d2-7883-8156-c4eb8a66bbe8" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_019e4c07-a6d2-78da-ad92-fa649500043f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019ed1de-c2a2-7c64-a3f6-e43c24898d14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e4c07-a6d2-74d5-ad49-da4987f2c544" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019ed1de-c2a2-7c64-a3f6-e43c24898d14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ed1de-c2a2-7c64-a3f6-e43c24898d14_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ed1de-c2a2-7c64-a3f6-e43c24898d14" xlink:to="loc_us-gaap_SegmentDomain_019ed1de-c2a2-7c64-a3f6-e43c24898d14_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ed1de-c2a2-73bd-aa77-b6086765d3d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ed1de-c2a2-7c64-a3f6-e43c24898d14" xlink:to="loc_us-gaap_SegmentDomain_019ed1de-c2a2-73bd-aa77-b6086765d3d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_ReportableSegmentMember_019ed1de-ec30-7c16-ad27-3a0b9eece93c" xlink:href="cubi-20260630.xsd#cubi_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ed1de-c2a2-73bd-aa77-b6086765d3d0" xlink:to="loc_cubi_ReportableSegmentMember_019ed1de-ec30-7c16-ad27-3a0b9eece93c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019e4c07-a6d2-7d4f-9a2e-7386b55415bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_NumberOfReportableSegments_019e4c07-a6d2-7d4f-9a2e-7386b55415bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_019e4c07-a6d2-7599-9b55-a40d292581a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperating_019e4c07-a6d2-7599-9b55-a40d292581a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOperating_019e4c07-a6d2-7c81-a415-31163e84c404" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_InterestExpenseOperating_019e4c07-a6d2-7c81-a415-31163e84c404" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_019e4c07-a6d2-75df-b6c1-dcc188e8e9c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_019e4c07-a6d2-75df-b6c1-dcc188e8e9c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversalIncludingPortionOfAvailableForSaleSecurities_019e4c07-a6d2-7da6-9167-ad9b9282e64c" xlink:href="cubi-20260630.xsd#cubi_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversalIncludingPortionOfAvailableForSaleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_cubi_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversalIncludingPortionOfAvailableForSaleSecurities_019e4c07-a6d2-7da6-9167-ad9b9282e64c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_019e4c07-a6d2-70d7-a262-6ff06d2b29b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_019e4c07-a6d2-70d7-a262-6ff06d2b29b6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncome_019e4c07-a6d2-75a7-be06-ca2e1f8a3f58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_NoninterestIncome_019e4c07-a6d2-75a7-be06-ca2e1f8a3f58" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_019e4c07-a6d2-72c4-b111-5685362742ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_LaborAndRelatedExpense_019e4c07-a6d2-72c4-b111-5685362742ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommunicationsAndInformationTechnology_019e4c07-a6d2-7ddf-af44-a45028c4e227" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommunicationsAndInformationTechnology"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_CommunicationsAndInformationTechnology_019e4c07-a6d2-7ddf-af44-a45028c4e227" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_OperatingLeasesCommercialLeaseDepreciation_019e4c07-a6d2-77bc-a0bd-1d20d8eeb1fe" xlink:href="cubi-20260630.xsd#cubi_OperatingLeasesCommercialLeaseDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_cubi_OperatingLeasesCommercialLeaseDepreciation_019e4c07-a6d2-77bc-a0bd-1d20d8eeb1fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_019e4c07-a6d2-702e-8595-2bc4ed8de43f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfessionalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_ProfessionalFees_019e4c07-a6d2-702e-8595-2bc4ed8de43f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanProcessingFee_019e4c07-a6d2-7369-be08-e45f6ba2afca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoanProcessingFee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_LoanProcessingFee_019e4c07-a6d2-7369-be08-e45f6ba2afca" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_019e4c07-a6d2-7203-8959-51fb17ab7bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OccupancyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_OccupancyNet_019e4c07-a6d2-7203-8959-51fb17ab7bf6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_FdicAssessmentsTaxesAndRegulatoryFees_019e4c07-a6d2-7596-a312-d749346f644b" xlink:href="cubi-20260630.xsd#cubi_FdicAssessmentsTaxesAndRegulatoryFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_cubi_FdicAssessmentsTaxesAndRegulatoryFees_019e4c07-a6d2-7596-a312-d749346f644b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketingAndAdvertisingExpense_019e4c07-a6d2-7290-8cec-b6646e25904e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketingAndAdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_MarketingAndAdvertisingExpense_019e4c07-a6d2-7290-8cec-b6646e25904e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoninterestExpense_019e4c07-a6d2-7a57-966c-fd68de8b2e76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNoninterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_OtherNoninterestExpense_019e4c07-a6d2-7a57-966c-fd68de8b2e76" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestExpense_019e4c07-a6d2-7155-99b5-c6fc178e9cff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_019e4c07-a6d2-7bcd-96c4-706fee99b0f2" xlink:to="loc_us-gaap_NoninterestExpense_019e4c07-a6d2-7155-99b5-c6fc178e9cff" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e4c07-a6d2-7dce-94a0-e9425c062163" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e4c07-a6d2-7dce-94a0-e9425c062163" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e4c07-a6d2-7435-acd9-9bc737f9333e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e4c07-a6d2-7435-acd9-9bc737f9333e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e4c07-a6d2-7fa3-a88e-8d997885c1a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_NetIncomeLoss_019e4c07-a6d2-7fa3-a88e-8d997885c1a5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_019fc89d-0464-78f3-ae6b-8a8e04488564" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_019fc89d-0464-78f3-ae6b-8a8e04488564" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockRedemptionPremium_019ed1b7-9ba6-7caf-b2fc-52cfb67667b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockRedemptionPremium"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_PreferredStockRedemptionPremium_019ed1b7-9ba6-7caf-b2fc-52cfb67667b8" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e4c07-a6d2-7016-87e4-726a14e8e23d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e4c07-a6d2-7016-87e4-726a14e8e23d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e4c07-a6d2-765d-b9f2-2e1083cad32a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e4c07-a6d2-765d-b9f2-2e1083cad32a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e4c07-a6d2-786a-b65d-743cdbe93dcd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e4c07-a6d2-786a-b65d-743cdbe93dcd" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_cubi_DepreciationOccupancyandAmortizationofLeaseholdImprovement_019e4c07-a6d2-77ba-94b0-bafeed26df53" xlink:href="cubi-20260630.xsd#cubi_DepreciationOccupancyandAmortizationofLeaseholdImprovement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_cubi_DepreciationOccupancyandAmortizationofLeaseholdImprovement_019e4c07-a6d2-77ba-94b0-bafeed26df53" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e4c07-a6d2-7deb-81c0-ee1be80532a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e4c07-a6d2-7c26-b68f-2cf5757b6734" xlink:to="loc_us-gaap_Assets_019e4c07-a6d2-7deb-81c0-ee1be80532a5" xlink:type="arc" order="17"/>
  </link:definitionLink>
</link:linkbase>
