David Laury added 25 points and 10 rebounds for Iona (11-5, 4-1 Metro Atlantic Athletic Conference). Williams hit 9 of 13 from the floor and hauled in in six rebounds while also dishing out five assists.
Trailing by as many as nine late in the first half, Iona closed the gap with a 12-5 run and headed into the break tied at 43 with Kelvin Amayo's layup just ahead of the buzzer. The second half featured nine lead changes before Williams put the Gaels ahead for good with his sixth 3-pointer of the game to make it 75-72 with 1:21 left.
Canisius (8-7, 3-3) shot 51 percent and controlled the glass 37-33 but got 10 fewer points from the foul line. Zach Lewis led the Griffins with 16 points.