The Bearcats (10-4, 3-0 America East) have won six straight games.
Maurice Joseph had 17 points for the Catamounts (9-5, 0-1), who had won six of eight.
With the game tied at 75, Rivera missed free throw with 10 seconds left in regulation.
He converted a three-point play to give Binghamton a one-point lead in overtime and Alvin followed with a 3 for an 81-77 lead with 3:50 left.
Rivera scored five points and the Catamounts missed two layups and four 3-point attempts in the final 61 seconds.