Playing without the injured Joel Embiid, the 76ers put up a far better fight than in the Knicks' 137-98 romp in Game 1. The game featured 25 lead changes - the most in a playoff game in 11 years - and 14 ties. Neither team led by more than seven points.
But those kinds of situations are made for Brunson, who made the tiebreaking basket with 5:06 remaining and added another jumper for a 103-99 advantage with 3:45 to play before Mikal Bridges' basket made it a six-point game.
OG Anunoby added 24 points for New York, though he wasn't on the floor at the end. It was unclear if he had been hurt.
Karl-Anthony Towns had 20 points, 10 rebounds and seven assists for the Knicks, whose Game 1 victory made them the first team to win three straight postseason games by at least 25 points.
Tyrese Maxey scored 26 points for the 76ers, who face another big climb after falling behind 3-1 against Boston in the first round.
The series moves to Philadelphia for Game 3 on Friday and Game 4 on Sunday, where Embiid will find out if gets his wish for the arena to be filled with Sixers fans or if New Yorkers made their way in.
Embiid was ruled out with right hip and ankle injuries after waking up with soreness and being unable to go through the 76ers' morning shootaround.
But the 76ers, who won Game 2 in Boston without him while he was still recovering from a late-season appendectomy, got 19 points each from Paul George and Kelly Oubre Jr. and 17 from VJ Edgecombe to nearly overcome their big man's absence.
They were ahead for the final time at 99-96 after Oubre's 3-pointer before Josh Hart - who had appeared to hurt his left hand or wrist in the third quarter and left the game - made a 3-pointer with 6:52 remaining.
The 25 lead changes were the most since the Spurs and Clippers combined for 31 on May 2, 2015.
Maxey managed only 13 points in Game 1 but was back to leaving defenders in the dust Wednesday, scoring 15 points in the second quarter and 19 in the first half.
The Knicks did a better job on him in the second half, led by Bridges, who also contributed 18 points.