Josiah Heath chipped in 11 points for the Griffins (7-4), who had 20 assists on 26 made field goals and shot 46.4 percent from the field. Valenti went 8 of 13 overall and was one of three starters with four assists.
Martez Harrison led UMKC (5-10) with 23 points, going 5 of 11 overall and 12 of 15 on free throws. The Kangaroos were limited to 15-of-48 shooting (31.3 percent) and no other player had more than six points.
Canisius pushed out to an eight-point lead after Valenti's jumper, but UMKC reeled off nine straight points to take the lead on Noah Knight's free throws midway through the second half. The Griffins later used a 14-1 surge sparked by three layups from Valenti to seal it.