Thrashers General Manager Don Waddell said terms of the deal with Chelios wouldn't be disclosed.
The veteran defenseman, who has played on three Stanley Cup championship teams, has won the Norris Trophy as the NHL's top blueliner three times. This year he has appeared in 44 games with the Chicago Wolves of the American Hockey League, recording 21 points (five goals, 16 assists) while ranking second in the league with a plus-35 rating.
A native of the Chicago area, Chelios has racked up 948 points (185 goals, 763 assists) and 2,891 penalty minutes in 1,644 career NHL games over 25 years with the Detroit Red Wings, Chicago Blackhawks and Montreal Canadiens.
He holds the record for most career playoff games (266), collecting 144 post-season points (31 goals, 113 assists) while winning the Stanley Cup with Montreal (1986) and twice with Detroit (2002 and 2008).