Isaiah Williams added 10 points and 12 rebounds for Iona (7-6, 4-0 Metro Atlantic Athletic).
After posting a 32-27 halftime lead, English, Williams, Washington and Aaron Rountree scored all of Iona's 33 points in the second half. Taylor Bessick was the only other Gaels player to score with four first-half points. Rountree finished with 10.
Iona sped to a 10-2 lead after a Washington layup before Niagara used an 11-2 run to take the lead on Marvin Prochet's 3-pointer with 9:49 left before halftime.
Emile Blackman's 3 shaved Iona's lead to 49-47 with 9:47 left but Niagara only made two field goals the rest of the way.
Prochet led Niagara (3-12, 1-3) with 11 points and six boards. Dominic Robb had 10 points for the Purple Eagles.