Smith signed a contract with Atlanta on Sunday, Aaron Wilson of KPRC 2 Houston reports.
Smith was released by the Bills last October after serving a six-game suspension for violating the league's policy against performance-enhancing substances. However, he ended up finishing the season in Tennessee, seeing all his work on special teams and collecting six tackles in five games. He'll likely work to earn a depth role in the Falcons' linebacker corps while continuing to be a presence on special teams.