Mitchell had been out since Game 6 of Los Angeles' first-round series against San Jose. He had one goal and 11 assists in 76 games for the Kings during the regular season.
Fellow defenseman Robyn Regehr remained out with an injury Sunday. He has missed the Kings' last seven games.
For the Blackhawks, defenseman Michal Rozsival is active after he was a healthy scratch for the last two games of their second-round series against Minnesota.