Glen Davis had 17 points and eight rebounds, and Sasha Pavlovic added a season-high 19 points as the Celtics snapped a two-game losing streak despite resting their starters for the second straight game.
Amare Stoudemire played 20 minutes and scored 14 points for New York, which will return to Boston to open the Eastern Conference postseason on Sunday night.
A crowd of 18,624 that came to see Kevin Garnett, Paul Pierce and Ray Allen instead got Von Wafer, Carlos Arroyo and Pavlovic. The Knicks sat Chauncey Billups and Carmelo Anthony, though Stoudemire played the entire first quarter and eight more minutes in the third.
Boston's first-round draft pick who had scored a total of 32 points in 30 games this season, Bradley shattered his previous career high of five points. Wafer and Jeff Green had 14 points apiece, and Nenad Krstic had 13 for the defending Eastern Conference champs.
Boston (56-26) finished the regular season with the No. 3 seed in the East. The Knicks (42-40) made the playoffs for the first time since 2004, finishing sixth in the conference.
Boston led 84-74 before the Knicks scored eight straight points near the end of the third quarter. But the Celtics scored the first 11 points in the fourth to pull away.
Notes
The Celtics were wearing special warmups to acknowledge Monday's Boston Marathon. … Celtics who didn't dress: Allen, Garnett and Shaquille O'Neal. Knicks who didn't dress: Billups, Anthony and Andy Rautins. Pierce and Rajon Rondo sat on the bench in uniform but did not play. … Green gave the pregame fan appreciation talk usually given by Pierce. … Pavlovic drew a technical in the third quarter for his response to Bill Walker's flagrant foul on a 3-pointer. Pavlovic, who made the basket, got two shots to make one free throw.