The Bluejays (20-4, 10-2 Big East) have won five of six and 15 of 17, and are now within a half game of No. 6 Villanova in the conference standings.
Kellen Dunham had 16 points and Alex Barlow added 13 for Butler (12-13, 2-11), which has lost four straight.
After leading most of the first half, Creighton found itself in a back-and-forth struggle most of the second half and couldn’t fend off Butler’s charges until McDermott hit the 3 to make it 64-63.
Andrew Chrabascz had two chances to give Butler a late lead but twice lost the ball and a 3 from Dunham that might have forced overtime was short.