<?xml version="1.0" encoding="US-ASCII"?>  
<!-- Generated by CompSci Transform (tm) - http://www.compsciresources.com -->    
<!-- Created: Wed Apr 01 19:22:33 UTC 2026 -->  
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">  
  <roleRef xlink:type="simple" xlink:href="wex-20260401.xsd#wex_r_AdditionalDimensions" roleURI="http://www.wexinc.com/role/AdditionalDimensions"/>   
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#PvpAdjustmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly"/> 
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/> 
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>    
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>     
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>   
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>   
  <definitionLink xlink:role="http://www.wexinc.com/role/AdditionalDimensions" xlink:type="extended"/>   
  <definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="extended">  
    <loc xlink:type="locator" xlink:label="ecd_AllAdjToCompMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllAdjToCompMember"/>   
    <loc xlink:type="locator" xlink:label="wex_yearendOverGrantDateChangeInFairValueOfEquityAwardsGrantedDuringTheCoveredYearThatRemainOutstandingAndUnvestedAsOfTheCoveredYearendMember" xlink:href="wex-20260401.xsd#wex_yearendOverGrantDateChangeInFairValueOfEquityAwardsGrantedDuringTheCoveredYearThatRemainOutstandingAndUnvestedAsOfTheCoveredYearendMember"/>     
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllAdjToCompMember" xlink:to="wex_yearendOverGrantDateChangeInFairValueOfEquityAwardsGrantedDuringTheCoveredYearThatRemainOutstandingAndUnvestedAsOfTheCoveredYearendMember" order="5" xbrldt:closed="true"/>     
    <loc xlink:type="locator" xlink:label="wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatAreOutstandingAndUnvestedAsOfTheCoveredYearendMember" xlink:href="wex-20260401.xsd#wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatAreOutstandingAndUnvestedAsOfTheCoveredYearendMember"/>  
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllAdjToCompMember" xlink:to="wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatAreOutstandingAndUnvestedAsOfTheCoveredYearendMember" order="7" xbrldt:closed="true"/> 
    <loc xlink:type="locator" xlink:label="wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatVestedInTheCoveredYearMember" xlink:href="wex-20260401.xsd#wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatVestedInTheCoveredYearMember"/>    
<!-- [WMV6][Q94GSPujS+3o+1U/hcixxhw3FK/iWc+CxGMz7KAYHIsUs4UPHMg/i3Q+NKkG3UJHF6jWPUa28lueAZts7ZmxOfawFv1aClP1L/qif6dhmJ6nPtyKFe6hGzu/iUkRb6w6Kkn1ffivUFULEhVM0nz9bdSDUHk780w2c7RhqvVHTEBtiujZwqSrqeyJgN4AHEvjVOuJArtFtUmcZaUA8j1/dkxZ67H5fUndsavmZrQgysS+oiPwJxYR06UwbqzECfRR9m2qoDNsFOuIRORdox1JiYZjHxaWed9n0CsoG1O50089Z65R5LmsNXAUGyjhf4EXknOfIf4r8m8=] CSR-->   
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllAdjToCompMember" xlink:to="wex_yearOverYearChangeInFairValueOfEquityAwardsGrantedInPriorYearsThatVestedInTheCoveredYearMember" order="9" xbrldt:closed="true"/>  
  </definitionLink>     
</linkbase>
