The game was close throughout, but the Colonials (17-8, 8-4 Northeast Conference) rallied from a five-point halftime deficit and outscored the Mountaineers 39-29 in the second half to seal the win.
It was tied 59-all with 2 minutes to play, but Lijah Thompson dropped in a layup after a timeout and Myers went 4-for-4 from the foul line down the stretch to seal it for Robert Morris.
Robert Morris outshot Mount St. Mary's from the floor 53.3 percent (24 of 45) to 39.1 percent (18 of 46) in the contest.
Velton Jones, who sank the Colonials' final two foul shots, finished with 10 points. Robert Morris snapped a two-game slide with the win.
Julian Norfleet led the Mountaineers (6-17, 4-8) with 23 points.