Julius Randle added 31 points and nine rebounds for the Knicks, who also received 29 points and 11 rebounds from RJ Barrett.
Jayson Tatum had 40 points, 11 rebounds and six assists for the Celtics, who have lost their last two home games.
Bennedict Mathurin scored 17 points, Myles Turner added 16 and Chris Duarte had 15 for Indiana.
Kelly Oubre Jr. scored 17 points for Charlotte, which dropped its third straight.
Walker Kessler (17 points, 10 rebounds) and Kelly Olynyk (15 points, 10 rebounds) each had double-doubles in the loss.