The Colonials (20-8, 11-4 Northeast Conference) had a season-high 19 steals to remain unbeaten in the five-game series with the Bulldogs (2-25, 1-14).
Robert Morris matched its season high by forcing 25 turnovers and had a 26-7 edge in points off turnovers.
Bryant posted its fewest points since a 91-38 loss to the Colonials on Feb. 3, 2011.
Robert Morris, which won the previous matchup 84-53 on Jan. 5, took its biggest lead at 69-35.
Lijah Thompson added 13 points in only 14 minutes of playing time and Lawrence Bridges chipped in 10 for the Colonials, who outshot the Bulldogs 40 percent (24 of 60) to 31.6 percent (12 of 38).
Frankie Dobbs scored 11 points and Alex Francis 10 to lead Bryant, which has lost 12 straight.