Earlier this week, Chicago declined to extend a $7.1 million qualifying offer to Dunn, making him an unrestricted free agent.
A defensive specialist, Dunn is expected to be a valuable addition to an offensive-minded Hawks team, led by All-Star point guard Trae Young.
The No. 5 overall pick in 2016, Dunn averaged just 7.3 points on 25.9% shooting from three last season. His 2.0 steals per game were second in the League, and the 26-year-old was the only player in the top-10 who played fewer than 25 minutes per game.