Old Dominion (10-1) broke a 39-all tie with a 13-1 run ending on Jonathan Arledge's jumper to make it 52-40 with 7:57 left.
The Monarchs extended their lead to 14 with 3:16 left, but William & Mary (6-4) had an 11-2 run to get within 63-58 on Omar Prewitt's 3-pointer with 1:42. The Tribe missed their next three 3-point attempts and the Monarchs made 6 of 7 free throws in the final minute.
Denzell Taylor had 10 rebounds and Old Dominion outrebounded William & Mary 41-24.
Marcus Thornton had 22 points, Daniel Dixon scored 16 and Prewitt added 15 for the Tribe. Those three took 36 of William & Mary's 46 field-goal attempts.