"Ex for a Reason" is a song by American singer Summer Walker with rapper JT of hip hop duo City Girls, released on October 15, 2021, as the lead single from Walker's second studio album, Still Over It (2021).

Summer Marjani Walker is an American R&B singer. She signed with the Atlanta-based record label Love Renaissance, an imprint of Interscope Records in late 2017. The following year, she released her debut commercial mixtape Last Day of Summer (2018), supported by its lead single, "Girls Need Love." The song became her first entry on the Billboard Hot 100 and spawned a remix featuring Canadian rapper Drake. Her debut studio album, Over It (2019) was met with critical and commercial success, peaking at number two on the Billboard 200 chart—briefly breaking the record for the biggest debut streaming week for a female R&B artist—and receiving double platinum certification by the Recording Industry Association of America (RIAA).