After months of rumor and speculation, Peyton Manning surveyed the landscape of his brilliant career and called one last audible.

He is retiring a champion.

A month after his Denver Broncos vanquished the Carolina Panthers in Super Bowl 50, Manning informed GM John Elway he is riding off into that orange sunset just like the Broncos' boss did 17 years ago after winning his second Super Bowl.

Just shy of 40, Manning will forgo $19 million and a 19th season in the NFL, where he served as both a throwback and a transformer during a glittering career bookmarked by an unprecedented five MVP awards and dozens of passing records.

"Peyton was a player that guys wanted to play with," Elway said. "That made us better as a team and I'm thrilled that we were able to win a championship in his final year."

Manning leaves the league he helped popularize to supersize status as its all-time leading passer and winningest starting quarterback - the only one in NFL history to win Super Bowls with two franchises.

His first came in 2007 with the Indianapolis Colts, who drafted him No 1 overall in 1998. The Colts gave up on him in 2012 after a series of neck surgeries forced Manning to miss all of the 2011 season and left him without feeling in the fingertips of his right hand.

Manning resettled in Denver where, despite a right arm weakened by nerve damage, he went 50-15 with his fifth MVP award and two trips to the Super Bowl in four seasons.

There will be no more showdowns with New England quarterback Tom Brady or matching wits with Patriots' coach Bill Belichick - against whom he was just 6-11, but 3-2 in AFC championships.

"I get asked a lot about my legacy," Manning said before the Super Bowl. "For me, it's being a good teammate, having the respect of my teammates, having the respect of the coaches and players. That's important to me. I am not taking this for granted. I just love football."

The 18th season for No 18 was by far his most trying. He had to adjust to new coach Gary Kubiak's run-based offense, to unrelenting health issues and to questions about his character.

Manning, whose dry wit and star power has made him a staple of commercials and late-night television for nearly two decades, saw his squeaky-clean image take a beating as the final pages were flipped on his storied career.

The NFL is investigating allegations that human growth hormone was shipped to his home in his wife's name following an Al Jazeera report that Manning dismissed as "garbage".

In a new lawsuit filed last month, Manning was cited as an example of a hostile environment for women at the University of Tennessee for his alleged harassment of a female trainer in 1996.

A torn ligament in his left foot hampered Manning all the way back to August. It led to his worst statistical season and sidelined him for six weeks before that fairy-tale finish in Santa Clara, California, when his defense carried him across the finish line.

"He had to do several things different this year," said his dad, Archie, a former star NFL quarterback.

"He had to take time off during the season, which he'd never done before. He ran the scout team, which I don't think he'd ever done, and he dressed as a backup, which he'd never done."

Manning also had to play the role of game manager for the first time during Denver's defense-fueled run to the title. "I'm just glad I was on the same team as our defense," he said.

Although his teammates said his speech on the eve of the game felt very much like a goodbye, Manning did not call it his "last rodeo" right away, saying he needed time to reflect.

Denver gained only 194 yards against the Panthers, the fewest for a victorious team in a Super Bowl, and Manning had a mere 13 completions for 141 yards.

Thanks to a defense led by game MVP Von Miller, however, Manning became the oldest quarterback to win a championship.

Manning, who revealed at the Super Bowl that he faces a hip replacement in retirement, finished in a tie with Brett Favre for most regular-season wins with 186.

His victory in Super Bowl 50 was his 14th in the postseason, one more than Favre, making him the NFL's only 200-win quarterback.

"There's no question that his work ethic is what made him into one of the greatest of all time," Elway said.

"All the film study Peyton did and the process that he went through with game planning and understanding what the other teams did was second to none."