The Tigers (17-15) got 15 points and nine rebounds from KeShawn Murphy, 14 points from Keyshawn Hall and 13 from Tahaad Pettiford.
Auburn advances to face fifth-seeded Tennessee (21-10) on Thursday afternoon.
Defense has been a struggle for the Tigers but Mississippi State’s point total was the fewest scored against Auburn by an SEC team this season. Auburn out-rebounded Mississippi State 43-39 and had seven turnovers to the Bulldogs’ 11.
Mississippi State (13-19) got 22 points from Josh Hubbard, its leading scorer who had 46 against Auburn in the regular-season matchup and 42 in Saturday’s loss to Georgia. But Hubbard was 8-of-25 from the floor and missed both of his second-half 3-point attempts.
Jayden Epps, Mississippi State’s second-leading scorer, was 6-of-16 from the floor with 14 points.
Auburn fell behind by eight early in the second half, but Overton’s four 3-pointers highlighted a 21-2 run which gave the Tigers a 51-40 lead with 13:13 left.
The Bulldogs got within three twice, but Auburn responded each time with a scoring run to extend its lead once more.
Another Overton 3, his sixth and the team’s 11th, with 3:03 left gave the Tigers a 71-59 advantage.
Mississippi State led 33-30 at half behind 13 points from Hubbard, who was 5-of-14 from the floor.
Auburn shot 35.7% from the floor in the first period as Murphy and Overton led the Tigers with seven each.
Murphy, who spent the last three years at Mississippi State, hit his first three shots and scored all of Auburn’s points in a 7-2 run to start the game.
But Murphy was whistled for a technical foul for taunting the Mississippi State bench just 1:50 into the contest after hitting a 3 at the end of the run.
That ignited a 31-16 run by the Bulldogs, who led 33-23 with 2:34 left in the half. Auburn scored the half’s last seven points to cut into the deficit.
