Damon Martin at MMAFighting.com is reporting that CM Punk has notified UFC that he has retired from mixed martial arts. Punk had to inform UFC of this so that he could be removed from UFC's anti-doping program. He was tested six times in 2020.
This is not a surprise since he hasn't fought in UFC since 2018 and Dana White indicated at the time that Punk would likely not be back unless he got some wins in smaller promotions.
Punk's second and last UFC fight was at UFC 225 where he lost to Mike Jackson via unanimous decision. Punk began training under Duke Roufus' Roufusport academy in 2014 and he was scheduled to make his MMA debut a year later but a back injury delayed those plans to 2016.
Punk has a 0-1 record in UFC with one no-contest. His loss to Mike Jackson was overturned because of Jackson testing positive for marijuana.