The team appeared to confirm the move Sunday on Twitter.
Treadwell's deal with Atlanta is a one-year pact, according to Josina Anderson of ESPN.
A first-round pick of the Minnesota Vikings in 2016, Treadwell has disappointed through his first four NFL seasons. He's amassed just 65 catches for 701 yards and two touchdowns in 53 games.
Minnesota released Treadwell this past August but re-signed the 24-year-old one month later. The Ole Miss product posted only nine receptions for 184 yards and one score in nine appearances last season.
The addition of Treadwell will give the Falcons' offense 11 former first-round selections:
Additionally, Atlanta has re-signed veteran cornerback Blidi Wreh-Wilson on a one-year extension, the team announced Sunday. Wreh-Wilson, who's been with the club since 2016, started two games in 2019.