Summer Marjani Walker (born April 11, 1996) is an American R&B singer-songwriter. Born and raised in Atlanta, she signed with the local 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 triple platinum certification by the Recording Industry Association of America (RIAA).

Her second album, Still Over It (2021) debuted atop the Billboard 200. The album broke the record for most streams in a single day by a female artist on Apple Music and broke her previous record for largest streaming debut-week for a female R&B artist; she also matched Taylor Swift as the only female musical act to have 18 concurrent songs from one album enter the Billboard Hot 100. It spawned the single "Ex for a Reason" (with JT of City Girls), which peaked within the top 40 of the Billboard Hot 100, while its follow-up, "No Love" (with SZA and Cardi B), peaked within the top 15 and received platinum certification by the RIAA. Her 2023 single, "Good Good" (with Usher and 21 Savage) also entered the chart's top 40.

Her accolades include a Billboard Music Award, a IHeartRadio Music Awards, three Soul Train Music Awards, and two Grammy Award nominations. In 2022 Billboard Women in Music recognized Walker with the Chart Breaker Award for her achievement on Billboard charts. As of 2025, Walker has sold over 32 million certified units from the RIAA between albums and songs.