The Golden Gophers, whose only loss this season came against No. 1 Duke on Nov. 22, won for the 11th straight time.
Minnesota outscored Illinois 31-10 over the final 10 minutes to break open a close game with Coleman scoring 29 points on 10-of-16 shooting.
The Gophers improved to 15-1 and are 3-0 early in the Big Ten Conference race. Minnesota will travel to No. 5 Indiana on Saturday in another key league contest.
Andre Hollins had 22 points, eight rebounds and six assists for Minnesota while Trevor Mbakwe added 19 points. The Gophers hit 52 percent from the field and made 9-of-15 from 3-point range.
Illinois (14-3, 1-2) was led by Brandon Paul with 21 points.