With the win, Marquette (17-5, 8-2 Big East) moved one-half game ahead of No. 9 Syracuse for first place in the Big East. Syracuse plays at home Sunday against St. Johns.
Davante Gardner added 13 points for Marquette, which won for the 22nd straight time at home, the fifth-longest streak in the nation.
Worrel Clahar led a DePaul comeback midway through the second half as he scored eight points, including two long 3-pointers, to cut Marquette's lead to 77-73 with 4:43 remaining.
Marquette went inside to Gardner, who scored on a short jumper and was fouled. He hit the free throw to give Marquette an 80-73 lead with 4:28 remaining.
Trent Lockett then blocked Jamee Crockett's short jumper and Blue hit two free throws and Jamil Wilson nailed a 3-pointer with 2:31 remaining to give Marquette an 85-73 lead.
Brandon Young had 21 points and six assists for DePaul (10-13, 1-9), while Clahar and Donnavan Kirk added 16 points each.