Peterson also played for coach Mike Smith when Smith was the defensive coordinator in Jacksonville.
Peterson can play inside and outside LB, and with middle linebacker Lofa Tatupu battling a chest injury, Peterson will provide some depth for the Falcons.
Last year, Peterson played in 15 games with five starts. He made 27 tackles (16 solo) while adding one interception and two passes defensed. He has 1,611 tackles (953 solo), 21½ sacks, 19 interceptions, 52 passes defensed, nine forced fumbles and nine fumble recoveries during his 13-year NFL career.