Ray Allen recorded 11 of his 22 points in the final quarter, where the Celtics outscored the Knicks 38-24 to pull away for their 13th win in 14 contests.
Paul Pierce led his team with 26 points as Boston (42-10) returned to the court less than 24 hours after losing 110-109 in to a feisty Lakers team.
"It showed a degree of mental toughness tonight, it would've been easy to give in," Celtics coach Doc Rivers told reporters.
"We told them before the game it's going to be close and we have to make our run at the end.
"We hung around long enough to play basketball."
New York forward Al Harrington led all scorers with 27 points while David Lee added 18 points and pulled in 18 rebounds at the end of an eventful week for the Knicks (21-28).
Kobe Bryant scored 61 points for the Lakers on Monday, the most ever at Madison Square Garden, then Cleveland Cavaliers forward LeBron James lit up scoreboard with 52 points on Wednesday.
Both games ended in defeats but New York were hoping to erase those memories when they forged a 76-72 advantage through three quarters.
Allen, however, responded with six quick points early in the fourth and Boston went on a 13-3 run to grab a 101-89 lead with 2:34 remaining.
The Knicks had won six of seven before their latest three-game losing skid, including a 100-88 home victory over the Celtics in their previous meeting on January 4, and were hoping for a repeat performance of that triumph.
They started well enough with Harrington sparking New York early with 17 first-half points, including three 3-pointers in the second quarter, before Boston's defense settled in and made things more difficult in the second half.
"We talked more, we switched and didn't allow (Harrington) to get open shots," Pierce said. "I think that's the key. When you give him space and allow him to hit open threes he's tough to guard."
Boston held New York to just 41 percent shooting on the night.
Kevin Garnett had 15 points and 11 rebounds while point guard Rajon Rondo had 12 points and 10 assists for the Celtics, who are trying to avoid falling into a slump after losing to the Lakers.
The last time Boston fell to Los Angeles, 92-83 on Christmas Day, it offset a season-worst 2-7 run.
