The Bobcats (11-6, 2-2 Mid-American Conference) trailed 7-2 early before gaining control. They built their lead to as much as 17 points early in the second half.
Whittington hit 5-of-9 3-point attempts, while Tillman was 8-for-11 from the field. The Bobcats shot 49 percent.
Leon Williams had seven points, 10 rebounds and four assists in an all-around game for the Bobcats.
Al Fisher had 15 points, Haminn Quaintance 12 points and 12 rebounds and Mike Scott 11 points for the Golden Flashes (14-4, 3-1). They trailed 36-25 at the break, losing their early five-point lead when Ohio countered with a 14-2 run.
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.