| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<!-- XBRL Document Created with Wdesk from Workiva --> |
<!-- Copyright 2021 Workiva --> |
<!-- r:6c1b60be-d98c-4c1a-bb87-421ff5734b7b,g:a90294c9-a0f7-4c9c-b57c-0c60ee6eaa9c --> |
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"> |
| <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/> |
| <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/> |
| <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/> |
| <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/> |
| <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/> |
| <link:roleRef roleURI="http://www.bluebirdbio.com/role/Cover" xlink:type="simple" xlink:href="blue-20210420.xsd#Cover"/> |
| <link:definitionLink xlink:role="http://www.bluebirdbio.com/role/Cover" xlink:type="extended" id="i6a956d28a50440b9bbaef59527f41e31_Cover"/> |
| </link:linkbase> |