The Red Foxes (6-26) won for just the second time since a 65-59 win over Manhattan on Jan. 9 and will face No. 1 seed Fairfield (23-6) in the second round on Saturday.
Marist led 29-26 at halftime after holding the Purple Eagles to 7-of-25 shooting in the opening half (28 percent). The Red Foxes shot 58.6 percent from the floor (17 of 29) after the break and stretched their lead to as many as 13, 66-53, with 5:44 left to play.
Anthony Nelson scored 28 points, but was the only player in double figures for Niagara (9-23), which shot 18 of 56 from the floor (32.1 percent). Nelson went 9 for 22 from the field, while the rest of his teammates combined to go just 9 for 34.