The Vikings (22-9, 12-6) will have a bye into the semifinals March 3.
Cleveland State made 73.9 percent of its second-half shots (17 of 23) to pull away after leading 30-27 at halftime. Harmon sank a pair of 3-pointers and Anton Grady added five points as the Vikings used a 13-4 run to take a 55-42 lead with 9:37 remaining.
Wright State (13-18, 7-11) shot 38.5 percent (10 of 26) in the second half.
Jeremy Montgomery added 17 points, while Grady had 12 points and eight rebounds for the Vikings, who won their second in a row after a five-game losing streak.
Julius Mays scored 15 points and AJ Pacher 12 to lead Wright State.