Malcolm Brogdon scored 22 points, Justin Anderson re-emerged as a scoring threat and second-seeded
Anderson had 15 points on 4-of-6 shooting and Anthony Gill added 16 points as the Cavaliers (30-3) moved on to face No. 7 seed Michigan State on Sunday in the East Region.
Anderson, playing with his broken left pinky taped to his ring finger, scored for the first time since Feb. 7 against Louisville. He failed to score in two ACC Tournament games.
Like last year when Virginia avoided a historic upset and held on to beat 16th-seeded Coastal Carolina, the Cavaliers needed a late second-half push to advance.
Belmont (22-11) had clawed within two behind 25 points from Crag Bradshaw, but the Cavaliers outscored the Bruins 17-7 over the final 4:37 of the game.
Virginia came into the NCAA Tournament having lost two of their last three games.
The Cavaliers trailed 20-17 midway through the first half when Brogdon scored on a reverse layup igniting a 12-0 run.
Anthony Gill scored on a low post move before Anderson scored and was fouled on a fast break layup for a three-point play. Marial Shayok added a 17-footer and scored on a driving layup and drew a foul.
Virginia led by as many as 14 points in the second half, but Belmont wouldn't quit.
Mack Mercer and Bradshaw got the Bruins back into the game with a 10-0 run. Mercer scored on two layups and Bradshaw had a dunk on a defensive breakdown by Virginia and knocked down a 3-pointer from the right wing to help cut Virginia's lead to 51-48 with 11:15 remaining.
The emotional Bradshaw would later close the gap to 62-60 with 4:37 left behind consecutive 3-pointers, including one off the glass. He would finish 5 of 9 from 3-point range.
But the Cavaliers would never surrender the lead.
London Perrantes hit a jumper from just inside the 3-point arc to make it a two-possession game and Gill made two free throws to give the Cavaliers some breathing room.
Gill then scored on a give-and-go layup from Perrantes and drew a foul to push the lead to nine as the Cavaliers began to pull away.