Ridley, 26, has 27 catches for 255 yards and a touchdown this season.
In the days leading up to the game, which the Falcons won 27-20, Ridley was at practice Wednesday and then was not at practice Thursday and did not travel with the team to England.
At the time, the Falcons said they were supporting Ridley through his issue and did not offer further explanation.
Last Monday, Falcons coach Arthur Smith said Ridley was day-to-day.
Smith said Monday "he's back" and was a full participant at Monday's practice.
The Falcons also placed starting right tackle Kaleb McGary on the COVID-19 reserve list Monday, the first player to be on the list since the team became 100% vaccinated in mid-August. McGary going on the list opened up a roster spot for the team to activate left guard Josh Andrews, who had been on injured reserve with a broken hand.
If McGary were to miss Sunday's game at Miami, veteran Jason Spriggs could be the logical replacement, although the team does have Willie Beavers on the practice squad. Current left guard Jalen Mayfield, who replaced Andrews in the starting lineup when Andrews got hurt, took snaps at right tackle during training camp.