Smith, a 6-foot-10, 225-pound center, is a 14-year veteran. He was picked No.1 overall by the Golden State Warriors in 1995 and has played for nine teams.
Smith picked Atlanta over Cleveland Cavaliers, where here played last season and which was offering the same deal.
Smith averaged 10.8 points and 5.5 rebounds with the Cavs in their first round sweep of the Detroit Pistons. He has career averages of 11.6 points and 6.7 rebounds a game.