The Bluejays improved to 16-1 for the season and are 5-0 in the Missouri Valley Conference. Wichita State, at 4-0, is the only other unbeaten team in league play.
McDermott made 10-of-11 field goal attempts in the second half, during which he scored 28 points.
Creighton had only a one-point lead late in the opening period, but held Missouri State scoreless for the final 2 minutes of the first half and for the first 3 minutes of the second half. The Bluejays' lead was built to 12 during that stretch.
Creighton won its 10th in a row with a 57 percent shooting performance. Jahenns Manigat added 11 points and was the only other Creighton player in double figures.
Missouri State (5-12, 3-2) was led by Keith Pickens with 11 points.