The wagers were placed "during a five-day period in late November 2021 while Ridley was not with the team and was away from the club’s facility on the non-football illness list," the NFL said in a statement.
The league did not immediately detail which games Ridley wagered on or how it was done.
While sports betting has boomed since the Supreme Court in 2018 struck down a federal law that required states to ban gambling on games, there is no such legal wagering in Georgia.
The league, however, insisted that there's "no evidence indicating any inside information was used or that any game was compromised in any way."
On his verified Twitter page, Ridley said he bet $1,500 on games and that he "didn't have a gambling problem."
Coaches and teammates were not aware of the bets, the league said.
At the time, Ridley was on the team's inactive list for a "non-football injury." He said he needed to temporarily step away from football "to focus on my mental wellbeing."
“There is nothing more fundamental to the NFL’s success — and to the reputation of everyone associated with our league — than upholding the integrity of the game," NFL Commissioner Roger Goodell wrote in a letter to Ridley.
"This is the responsibility of every player, coach, owner, game official, and anyone else employed in the league. Your actions put the integrity of the game at risk, threatened to damage public confidence in professional football, and potentially undermined the reputations of your fellow players throughout the NFL."
The league said Ridley may petition for reinstatement on or after Feb. 15, just a few days after the Super Bowl.
Ridley, 27, a Florida native who starred at the University of Alabama, has played in 49 games over four seasons with the Falcons, catching 248 passes, good for 3,342 yards and 28 touchdowns.
He is far from the first NFL player to have been suspended because of gambling.
Then-Arizona Cardinals cornerback Josh Shaw was suspended from playing in the 2020 season for betting on games.
Green Bay Packers halfback Paul Hornung and Detroit Lions defensive tackle Alex Karras were famously suspended for gambling by then-NFL Commissioner Pete Rozelle, and they both missed the 1963 season.
When sports gambling was legalized in Indiana, Hornung made the state's first ceremonial bet in 2019.