Antwoine Anderson was fouled with 19 seconds left in regulation and split a pair at the line to give Fordham a 63-60 lead. UMass' Trey Davis drove the lane and kicked it out to Donte Clark for a 3-pointer in the corner with 8.1 seconds left to tie it at 63-all.
Fordham's Nemanja Zarkovic missed an open 3 at the buzzer.
In overtime, Christian Sengfelder hit a 3-pointer to extend Fordham's lead to 72-67 and after UMass missed a 3, Anderson hit two free throws for a seven-point advantage with 36 seconds left.
David Pekarek added 11 points for Fordham (12-8, 3-6 Atlantic 10), which snapped a seven-game conference road losing streak.
Davis led UMass (8-12, 1-7) with 21 points on 12-of-14 shooting at the stripe. Clark added 19 points.