Iona lost control of the ball on its final possession, but regained it from the scramble to set up the wide open 3 for English.
The Gaels (14-8, 11-2 Metro Atlantic) trailed 86-74 with 4 minutes left before using a 16-3 rally to avoid the upset and move alone into first place in the MAAC.
Wesley Myers extended the Niagara lead to 89-82 on a three-point play with 2:02 to go before Iona scored the last eight points.
Ramone Snowden had 18 points and 10 rebounds, and Wesley Myers added 16 points. The Purple Eagles (6-18, 3-10) had 21 offensive boards and outrebounded Iona 48-29 overall.