Dunleavy, who jammed his right ankle in Thursday’s win over Denver, hadn’t missed a game since joining the Bulls before the 2013-14 season.
Butler, who has played in 31 of 33 games this season, is out on bereavement leave.
Butler’s absence puts more pressure on point guard Derrick Rose to carry the offense.
Butler is in the midst of a breakout season, averaging a team-high 21.9 points to go with 6.2 rebounds and 3.3 assists. He had 26 points, eight rebounds and eight assists in the Bulls’ 106-101 win over Denver on Thursday.
He missed the team’s first two games of the season in October but since then has averaged 40 minutes per game.
Dunleavy is averaging 9.6 points while playing nearly 30 minutes a game. He’s shooting 41.7 percent on 3-pointers.
Chicago (23-10) is already without rookie small forward Doug McDermott, who had his knee scoped in December.