Brady, whose Tampa Bay Buccaneers team lost in the wildcard round of the NFL playoffs last month, made his announcement in a social media video, France24 reports.
"Good morning, I'll get to the point right away: I'm retiring for good," Brady said, sitting by a beach.
Brady won a record seven Super Bowls, six of them with the New England Patriots before adding his final triumph with Tampa in the 2020 season.
Brady had announced he was retiring on February 1, 2022, but 40 days later changed his mind and said he was returning for the 2022 season with the Bucs.
"I know the process was a pretty big deal last time, so when I woke up this morning I figured I'd just press record and let you guys know first. So I won't be long-winded," he added.
"I think you only get one super emotional retirement essay, and I used mine up last year. So, really, thank you guys, so much, to every single one of you, for supporting me.
"My family, my friends, teammates, my competitors, I could go on forever, there's too many. Thank you, guys, for letting me live my absolute dream. I wouldn't change a thing. Love you all," he said.