Chelios appeared in seven games with the Thrashers after being recalled from Chicago on March 10.
Chelios has played in more NHL games than any other American-born player. He won three Stanley Cups and was a three-time winner of the Norris Trophy as the league's top defenseman.
The Thrashers recalled Chelios last month in hopes he could provide a spark for the team's playoff hopes. Atlanta was eliminated from playoff contention with a loss to the New Jersey Devils on Tuesday night.
The Thrashers also assigned forward Tim Stapleton to Chicago.