Marcus Morris Sr. had 20 points and missed a half-court heave at the buzzer for the Knicks, who have lost three straight.
Josh Richardson added 18 points and reserve Furkan Korkmaz scored 17 for the 76ers, who snapped a six-game road losing streak. Their last win away from home was Dec. 23 at Detroit. Philadelphia is 28-16 overall but just 8-14 on the road.
Marcus Morris Sr. had 20 points and missed a half-court heave at the buzzer for the Knicks, who have lost three straight. Julius Randle had 14 points and 12 rebounds.
New York rallied late with a 10-2 run and took a 87-86 lead when Morris sank a jumper over Simmons with 31 seconds left in regulation.
Harris, who made just 5 of 13 shots and finished with 15 points, answered with his fourth 3-pointer of the night on the ensuing possession to put Philadelphia ahead 89-87 with 28 seconds to play.
New York had a chance to tie, but Philadelphia swarmed Randle on a inbound play and forced the ball out of bounds.
Korkmaz’s free throw with 4.2 seconds left sealed it for the 76ers.
Simmons had 16 points to help the 76ers build a 52-46 lead heading into the half. He shot 7 for 10 from the field and had couple of dunks in transition that brought the Madison Square Garden crowd to its feet, including a noticeable Philly contingent.
Two-time MVP Steve Nash watched from courtside.
Sixers: Matisse Thybulle has notched at least one steal and one block in his last five games. The last Philadelphia rookie to do so was Simmons during the 2017-18 season. Thybulle leads all NBA rookies with 16 games of at least one steal and one block.
Knicks: Reggie Bullock had 14 points and Elfrid Payton added 10 points, seven assists and seven rebounds.
Sixers: Visit the Brooklyn Nets on Monday before concluding their three-game trip at Toronto on Wednesday.
Knicks: Visit the Cleveland Cavaliers on Monday night.
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