Pierce went 10-of-18 from the field and Garnett contributed 19 points with 10 rebounds as Boston overcame the loss of suspended point guard Rajon Rondo to notch a season-high third consecutive victory.
Avery Bradley provided 13 points and five assists while subbing for Rondo, who was forced to sit out a game after making contact with a game official during Saturday's win at Atlanta.
Jeff Green came off the bench for 16 points as Boston limited the Knicks to a 40.8 percent shooting from the field.
Carmelo Anthony could hit only 6-of-26 of his field goal attempts en route to 20 points for New York.
J.R. Smith supplied 24 points in the Knicks' loss.