Zach Lewis scored 12 for the Griffins (8-6, 3-2 Metro Atlantic Athletic Conference), who shot 50 percent to 38.2 percent and outrebounded Marist 33-29.
The Griffins led 30-29 at halftime with Williams scoring 10 points.
Manny Thomas hit a 3-pointer and Marist led 34-32 early in the second half. The lead changed hands two more times before Jermaine Crumpton put the Griffins up 41-38 with a layup, sparking a 12-2 run. Marist stayed close with Phillip Lawrence and Obi Momah combining for three 3s, but Canisius used an 11-2 run to pull away down the stretch.