Garnett sat out after being suspended for hitting Milwaukee's Andrew Bogut during Boston's 102-97 overtime win on Saturday. The one-game suspension cost Garnett upwards of $200,000. Brian Scalabrine started in his place and had eight points, including a clutch three-pointer down the stretch.
Kendrick Perkins had 16 points for the Celtics, who have won two in a row and eight of nine overall. Rajon Rondo and Ray Allen scored 15 points each in the win.
Wilson Chandler scored 23 points for the Knicks, who have lost two straight and three of five overall. Zach Randolph had 18 points and eight boards, while Chris Duhon had 15 points and five helpers.
Down 12 late in the fourth, the Knickerbockers outscored the Celtics 8-3 to get back in the game.
Chandler, Nate Robinson and David Lee connected on consecutive baskets before Pierce nailed a three. Randolph then added a pair of free throws to make it 97-90 with 4:50 left in regulation.
A Duhon three-ball and Chandler layup pulled the Knicks within four points moments later, but Pierce hit a free throw and Scalabrine drained a three from the left wing to make it 107-99 and all but seal the win.
The Knicks edged the Celtics for a 28-26 lead after the first 12 minutes.
With Boston up by two, Glen Davis connected on a jumper that served as the first two of eight straight Celtics points. Allen's layup closed the run to give the home team a 47-37 lead with 5:21 left in the half.
As the second quarter came to a close, the Celtics held a 56-47 lead.
Two free throws from Pierce and a Eddie House jumper gave the Celtics an 89-77 lead heading into the fourth frame.