Fellow seniors Fuquan Edwin and Eugene Teague added 17 points apiece as the Pirates (15-15, 6-11 Big East) won their final home game and completed a sweep of Xavier (20-10, 10-7).
Semaj Christon scored 24 of his career-high matching 28 points in the second half for the Musketeers, who lost center Matt Stainbrook to an injury to his left knee in the first half. Isaiah Philmore added 11 points and nine rebounds.
Seton Hall also got five points, six assists and seven rebounds from senior Brandon Mobley in knocking off Xavier two days after it upset then No. 9 Creighton.
The Pirates, who led by as many as 14 points, held Xavier to 30 percent shooting, a season-low 20 points in the first half and 3-for-22 shooting from 3-point range in leading almost from start to finish.
Christon also single-handedly got Xavier back into the game in the second half, hitting his first seven shots. It helped cut a 13-point deficit to 57-52 when he hit two free throws with 5:24 to go.
The Musketeers trapped guard Jaren Sina in the backcourt and he fell to the floor after some contact. There was no call and the Pirates got the ball upcourt quickly with Edwin finishing with a three-point play. It ignited a 9-2 spurt and the game was basically decided.
Stainbrook came down hard on his left leg after being fouled taking a shot inside with 8:02 left in the first half. He immediately clutched his left knee and screamed in pain. He was on the floor for a couple of minutes and had to be helped to the locker room.
An MRI was planned for Tuesday and coach Chris Mack said he hoped it would not reveal a major injury. Stainbrook left the locker room on crutches and could not put any weight on his leg.
Philmore hit the two free throws in place of Stainbrook, the conference's No. 2 rebounder, getting the Musketeers to within 16-14.
The Pirates took over in the final eight minutes, outscoring Xavier 16-6 with Teague dominating inside and Oliver hitting from the outside.
Teague started the run with two free throws and Oliver followed with a 3-pointer and two more free throws to push the lead to 23-14.
After Xavier made consecutive baskets, Teague scored inside, Oliver hit a 3-pointer, Teague made a free throw and Oliver made his third 3-pointer of the half for a 32-18 lead.