The wrestling legend, 47, dropped the bombshell news at the Money in the Bank pay-per-view.
He plans to fight up to 40 events throughout 2025.
Cena slid into the ring in trademark fashion in Toronto, Ontario in Canada on Saturday.
But he quickly showed fans this was no ordinary entrance to a WWE ring.
Cena simply said as cited by Sports Central: "Tonight, I officially announce my retirement from the WWE."
He wore a resigned look on his face as he delivered the news to fans.
Huge gasps could be heard from the audience on the live TV feed.
Cena has been with the WWE since 2001 - and will quit the brand after 24 years.
He said: "I have been doing this a while, I've been in WWE for over two decades. "And in that time I've seen incredible waves of prosperity like we've got right now. "WWE is the hottest ticket in town, no doubt. And I've also seen tremendous hardship. "That's when noone knows your name, nobody wants to be a friend and only the most dedicated, hardcore fans stand by your side. "In all those years, one of the most important, impressive things that I learned was whether the WWE was hot or cold, Canadians always show up."
The entire arena broke out into chants of "Cena, Cena" and "Thank you Cena."
Fans on social media also reacted to the shocking news.
"A childhood hero," one wrote.
"Genuinely might cry," another posted.
"Thank you Cena. Wow man," a third said.
While one more commented, "I was not prepared for this news today."
Cena confirmed he will be part of WWE Raw's move to Netflix next year.
