The 76ers have defeated the Celtics in both their meetings this season, Turner having scored 25 points in a six-point decision over Boston on Nov. 19.
This time Turner produced 26 points, two of them coming with 45 seconds left in the fourth period that put the 76ers in front 89-87. Kevin Garnett then forced overtime by scoring on a hook shot with 8 seconds to go in regulation.
Boston had a one-point lead and the ball with time running out in the extra period, but Courtney Lee missed a 3-point shot with 26 seconds remaining.
That gave the 76ers a chance to win it, which they did on Turner's jumper. Boston's Rajon Rondo then missed a jump shot just before the buzzer.
Boston suffered the setback despite a triple-double from Rondo, who scored 16 points, grabbed 13 rebounds and handed out 14 assists. Paul Pierce had 27 points for the Celtics and Jeff Green scored 17 off the bench.
Philadelphia has played six games this year against its division opponents, more than any other team in the NBA. The 76ers have won four of those six.