Ali's second 3-pointer in 4 minutes gave Georgia State (10-14, 4-8 Colonial Athletic Association) a 58-57 lead with 48 seconds left and the Panthers sealed the game at the free throw line.
George Mason (15-8, 10-2) didn't score after Mike Morrison's layup gave the Patriots a 57-53 lead with 2:52 to play to snap a seven-game winning streak. They went 0-for-5 from the field in the final 2:08.
Georgia State's Joe Dukes hit two free throws with 2:37 left to cut the deficit to 57-55.
Ali was 9-for-13 from the field and hit both of his 3-pointers in the final 4:28. Dukes finished with 10 points and 10 assists.
Ryan Pearson led George Mason with 13 points and eight rebounds and Luke Hancock added 10 points.