Marist (4-18, 3-9 Metro Atlantic) made just one basket - with 15 seconds left - in the last seven minutes but Canisius went 4 of 16 down the stretch and was unable to make up a double-digit deficit.
The lead reached 13 with 7:37 left after a pair of free throws by Lewis. On the ensuing possession, Lewis had a steal and layup for the largest lead of the game.
Lewis was 14 of 16 from the floor and 6 of 12 from the line. Khallid Hart added 13 points.