Todd Abernethy scored 18 points and Mississippi held Appalachian State scoreless for nearly 6 minutes in the second half to pull away for a 73-59 victory Wednesday night in the first round of the NIT.
Clarence Sanders' steal and layup with 10:15 remaining began a 19-2 run to put the Rebels ahead to stay.
Mississippi (21-12), which won its first postseason game since reaching the round of 16 in the 2001 NCAA tournament, got 14 points and eight rebounds from Dwayne Curtis, and 13 points and 11 rebounds from Kenny Williams. Sanders scored 11.
The fourth-seeded Rebels will play at South region top seed Clemson on Monday.
D.J. Thompson scored 17 points and Donte Minter added 14 for Appalachian State (25-8), which was seeking the first postseason win in school history. Doug McLaughlin-Williams added 10 points.
Ole Miss had had 16 turnovers that the Mountaineers converted into 17 points. Appalachian State's reserves also outscored Ole Miss' bench players 28-9.
Abernethy was 6-for-12 from the floor, including two 3-pointers. His two free throws in the final seconds of the first half gave Ole Miss a 38-35 lead at the break.
The Rebels scored the game's first seven points and held the Mountaineers without a basket for nearly three minutes 17:10, when Minter scored the first of his 12 first-half points.
Sanders' three-point play with 11:35 left in the opening half put Ole Miss ahead 20-10, but the Rebels wouldn't hit another field goal for nearly 5 minutes as Appalachian State went on a 17-4 run.
Consecutive putbacks by Williams gave Ole Miss the lead back with 6:14 left in the half.
Ole Miss scored just 10 points over the first 10 minutes of the second half before outscoring the Mountaineers 25-10 to end the game.