Dwaun Anderson had a 3-pointer and Henson followed with a 4-point play to spark a 15-4 run that pushed Wagner (7-4) up 63-49 with 6:07 left. The Seahawks, who led by no less than 10 from there, made 54 percent of their shots.
Anderson finished with 13 points and Henry Brooks had 11 points and six rebounds.
UMass Lowell (4-9) jumped ahead 7-0 to start the game and Wagner quickly pulled ahead for good with a 16-4 response. The River Hawks hung close through the first half, though, and trailed only 48-45 on Matt Harris' 3-pointer with 10 minutes left.
Harris led Lowell with 15 points and Jahad Thomas added 13.