The Atlanta Falcons great -- who played all but one season with the organization -- released a heartfelt goodbye to the game on Monday ... saying it was time to hang up the helmet.

"Today, 16 years after being drafted, my childhood dream has officially come to an end," Ryan said.

"I'm honored to retire as a Falcon."

Ryan -- the third overall pick in 2008 -- played his best season in 2016 ... leading the league in passer rating and being named first-team All-Pro.

He threw for nearly 63,000 yards during his time under center ... and had 381 touchdowns and just 183 interceptions.

Ryan -- the franchise's all-time wins leader for a quarterback -- led the Falcons to a NFC Championship in 2017.

Ryan shouted out several members of the Falcons organization ... including owner Arthur Blank and teammates like Tony Gonzalez, Michael Turner, Roddy White and, of course, Julio Jones.

"I truly believe that football life is not simple about what you do but rather who you do it with and I was a better player because of the people I was surrounded by," Ryan added.

The four-time Pro Bowler played his final season with the Indianapolis Colts in 2022 ... going 4-7-1 in 12 games.

He spent the 2023 campaign working for CBS on NFL Sundays.