Butler, who was questionable to play due to a sprained left ankle, scored 18 of his 34 points in the fourth quarter and hit his second game-winner since joining Philadelphia in a trade from Minnesota on Nov. 12.
He gave Philadelphia the dramatic win when he took the inbounds pass from Ben Simmons, began to move slightly inside the 3-point arc, stepped back and released a 3-pointer in front of Brooklyn's bench with Rondae Hollis-Jefferson's hand in his face.
The Nets committed a turnover on the ensuing inbounds pass, and the Sixers celebrated their eighth win in 11 games.
Butler's shot capped a terrific finish for the Sixers, who led briefly in the opening minute and did not regain the lead until JJ Redick's 3-pointer with 1:03 remaining.
The lead changed hands five times in the final 63 seconds, and the Nets held a 125-124 edge on Spencer Dinwiddie's pullup jumper over Redick with 26 seconds left. After the Nets took their final lead, Redick's jumper went in and out of the hoop, but Butler won a jump ball from Hollis-Jefferson.
Philadelphia's Joel Embiid posted his league-leading 20th double-double with 32 points and 12 rebounds after attending the Jets-Patriots game in East Rutherford, N.J., earlier in the day. Rookie Landry Shamet added 16, Redick contributed 15 and Simmons had 13 as the Sixers pulled off their biggest comeback of the season by overcoming a 20-point deficit.
Brooklyn's D'Angelo Russell led all scorers with a season-high 38 points but did not score in the final 7:26. The Nets were outscored 24-12 the rest of the game and gave up an 11-0 run to allow Philadelphia to start its comeback.
Dinwiddie added a season-high 31, but the Nets lost their fourth straight home game. They had defeated the Sixers on Nov. 4.
Russell had 11 after the first quarter and 16 by halftime as the Nets took a 68-54 lead. He added 13 more by the end of the third quarter, when the Nets held a 102-89 lead, and surpassed 30 points with a floater early in the fourth to put Brooklyn in front 106-93.
Russell surpassed his previous season high by hitting a step back jumper for a 108-96 lead with 9:50 left. Then he reached 35 by hitting a 13-footer with 8:01 left to make it 110-100.
After a 3-pointer by Butler made it 110-103, Russell hit a 3-pointer with 7:26 remaining, and Brooklyn's collapse began a few minutes later.
--Field Level Media
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)