Keo resigned with the Broncos on Tuesday, Mike Klis of 9News.com reports.
Keo rejoins the team just a few days after they parted ways. The safety was suspended for the first two weeks of the season but is now able to take the field again. He'll compete with rookies Justin Simmons and Will Parks for a backup safety position.
Collins tallied 17 total tackles in 16 games during his rookie year with the Falcons.
Collins was limited to rotational work, only seeing the field on 28.6 percent of the total defensive snaps. He'll likely earn more playing time in the coming years, but the Falcons have a pretty young core of secondary players, meaning it won't be easy for Collins to ascend the ranks.