Indiana (47-17) ended its longest losing streak of the season at four. Paul George added 12 points as the Pacers extended their Eastern Conference lead to 1½ games over two-time defending champion Miami in the East.
Boston (22-42) was led by Jared Sullinger with 17 points and Kris Humphries with 15 as its two-game winning streak ended.
Bynum played just 15 minutes but his first basket gave Indiana a 16-14 lead and the Pacers never trailed again.
Boston, which trailed by as much as 15 in the third quarter, twice got within one in the fourth. But the Pacers answered the second time with a 6-0 run to make it 83-76 and the Celtics never threatened again.
Bynum gave Indiana an infusion of energy that it desperately needed on a night George was in foul trouble and Lance Stephenson was off the mark.
Through 2 ½ quarters, Stephenson and George had combined for just four points.
Bynum, on the other hand, finished with eight points and one assist in his first action since late December. And the fans, who had been waiting since Feb. 1 to see No. 17 on the court, gave him a rousing ovation when he entered the game with 4:22 left in the first quarter.
SPURS: Manu Ginobili scored 22 points and Tony Parker had 20 as league-leading San Antonio beat the Chicago Bulls 104-96.
Kawhi Leonard added 16 for San Antonio, which won its seventh in a row and 10th in its past 11.
The Spurs (47-16) maintained their hold on the NBA’s best record, staying ahead of Oklahoma City and Indiana, who both started play Tuesday a half-game behind the Spurs.
GRIZZLIES: Marc Gasol had 19 points, Zach Randolph added 18 points and 12 rebounds and Memphis solidified its hold on the final Western Conference playoff spot with a 109-99 victory over the Portland Trail Blazers.
SUNS: The NBA suspended forward P.J. Tucker for one game for elbowing Blake Griffin in the chin in the Suns’ loss to the Clippers on Monday night.
Tucker will sit out tonight’s home game against the Cleveland Cavaliers.
Tucker was ejected after the altercation. The elbowing occurred as the two fell to the floor entangled while going for a rebound with 5½ minutes to go in the game.