A dominant second half by the big man from Cameroon, in just his second game back after an April 9 emergency appendectomy, enabled the Sixers to pull within 3-2 in the best-of-seven Eastern Conference first round playoff matchup.
"It's kind of hard. I only had once chance to go up and back (on the court) before I came back," Embiid said. "Using this game and last game to kind of get back into it.
"I found my rhythm in the second half. We adjusted some stuff at halftime. I feel OK. I feel good. We got a win. That's all that matters."
The series shifts back to Philadelphia for game six on Thursday with a seventh game, if needed, in Boston on Saturday.
"We did our job," Embiid said. "We're going to need everybody to come back to Boston."
Embiid struggled with three-pointers early before dominating in the paint.
"When they got the lead early, we kept playing our game," Embiid said. "I missed a couple (outside) and I went inside and found some luck."
Tyrese Maxey added 25 points and 10 rebounds for the 76ers, who also had 16 points and nine rebounds from Paul George.
Jayson Tatum had 24 points and 16 rebounds for Boston, which also had 22 points from Jaylen Brown.
But the Celtics were outscored 28-11 in the fourth quarter, producing their fewest points in any quarter this season with the series clincher up for grabs.
The Celtics, chasing a second NBA title in three seasons, or 76ers will face either New York or Atlanta in the second round.
The Sixers have not won a playoff series since sweeping Brooklyn in the first round in 2023.
The Celtics, who have missed the playoffs only once since 2007, are trying to reach the second round for the fifth year in a row and ninth time in 10 seasons.
Boston led 57-50 at halftime but V.J. Edgecombe's three-pointer lifted the Sixers within 66-65 midway into the third quarter.
Embiid tweaked his left knee and went to the locker room late in the third quarter with the game on a knife's edge.
Boston went on a 7-0 run, but Embiid returned as the Celtics clung to an 86-85 lead entering the fourth quarter.
Embiid sparked the Sixers to a 102-94 lead, their largest of the game to that point, with 5:16 remaining and Boston could not recover.
The Knicks seized a 3-2 lead in their series with a 126-97 home victory over the Hawks.
Jalen Brunson scored 39 points on 15-of-23 shooting from the floor and added eight assists while Karl-Anthony Towns had 16 points and 14 rebounds for the hosts.
Atlanta must win at home in game six on Thursday to force a winner-take-all game seven in New York on Saturday.
In a later game, the San Antonio Spurs try to reach the second round with a home victory over Portland, which trails in their series 3-1.