“She Used to Be Mine” is a song written by American singer-songwriter Sara Bareilles for Waitress, her musical stage adaptation of the 2007 film of the same name. It was recorded by Bareilles for her fifth studio album, What’s Inside: Songs from Waitress (2015), and was released to digital retailers as its lead single on September 25, 2015. The song was recorded by Jessie Mueller for the cast recording of the Broadway production of Waitress in 2016, and performed by Mueller and Bareilles at the 70th Tony Awards. The song was also featured as a bonus track on country singer Jennifer Nettles’ Broadway album Always Like New ahead of her taking over the role of Jenna from Bareilles in October 2021.