Mosley hit 5 of 10 from 3-point range and 6 of 6 free throws for Old Dominion (6-1), which made a season-high 11 3-pointers and converted 20 of 23 free throws. Richard Ross added 13 points and a career-high 14 rebounds - 10 offensive.
After Marquise Moore gave George Mason (2-5) a 62-60 lead with 3:13 to play, Mosley scored eight-straight points and Old Dominion led by six about 2 minutes later.
Old Dominion made 5 of 6 free throws from there to seal it.
Moore led George Mason with 22 points.