After he retired from professional wrestling, Punk signed a deal to fight with the Ultimate Fighting Championship (UFC), and he began to pursue a career in mixed martial arts. He fought for them from 2015 to 2018. He returned to professional wrestling in 2021 by signing with All Elite Wrestling (AEW), where he won the AEW World Championship twice, but was fired in September 2023 after backstage controversies. He returned to WWE two months later at Survivor Series.