On Friday night's episode of Rampage, Punk, 43, revealed that he'd suffered an injury that will necessitate surgery just five days after becoming champion.
Punk will not relinquish the AEW world championship, but an interim champion will be crowned in his place.
Punk described the injury as a "broken wheel." He vowed to return bigger, faster, stronger, and more ravenous than ever before.
On Rampage, Punk spoke to the crowd with tears in his eyes. He stated that he had both good and bad news for his listeners.
"I've been injured and will require surgery," the grim news reads. There are a few items that aren't functioning properly.
My heart is the largest because I adore performing for all of you, and I wanted to go on a run unlike any other.
"The good news is that I can still handle everything." I promised I'd keep going till I couldn't anymore.
Punk won the AEW world championship by defeating Adam "Hangman" Page in the main event at Double or Nothing on Sunday.
On Wednesday, Punk suffered the injury while playing Dynamite. On the show, he paired up with FTR to beat Max Caster, Austin Gunn, and Colten Gunn.
The temporary AEW global champion will be awarded at AEW and NJPW's co-promoted Forbidden Door pay-per-view on Sunday, June 26.
Dynamite will kick out on Wednesday with a battle royal, with the winner going on to face Jon Moxley in the episode's main event, according to AEW.
The winner of that match will face an opponent who has yet to be disclosed for the interim title at Forbidden Door.
When he signed with AEW last August, Punk made his pro wrestling comeback seven years after quitting WWE. He hasn't won a global title since 2013.