Patterson agreed to a one-year deal worth $3 million, a source told Mike Garafolo of NFL Network.
The four-time first-team All-Pro is considered one of the greatest returners in NFL history. He's tied for the most kickoff-return touchdowns ever with eight, and Patterson owns the longest kickoff score at 109 yards.
The 30-year-old spent the last two seasons with the Chicago Bears, earning back-to-back first-team All-Pro nods. He led the league in kick-return yards in 2019 with 825, and in 2020 with 1,017.
Patterson rarely played as a receiver in Chicago, catching just 32 passes for 215 yards and zero touchdowns.
His career highs of 469 receiving yards and four receiving touchdowns came during Patterson's rookie season with the Minnesota Vikings in 2013.
The veteran has also been named to two second-team All-Pro squads, four Pro Bowl teams, and the NFL's 2010s All-Decade Team.
Atlanta desperately needed to bolster its return game after ranking 31st in kickoff yards with 409 in 2020.
The Falcons also announced the signing of safety Duron Harmon on Thursday. Harmon started 16 games for the Detroit Lions last season following a seven-year stint with the New England Patriots.