Ray Allen and Shane Battier combined for 24 points in the fourth quarter, and the Heat scored the first 13 points of the period to erase Atlanta's 10-point lead and beat the Hawks 103-90 on Wednesday night for their eighth consecutive win.
LeBron James had 24 points. Miami outscored Atlanta 40-17 in the final period as Allen and Battier combined for five 3-pointers.
"Ray has proven that he has been one of the elite fourth-quarter players in the league for a long time," said Miami coach Erik Spoelstra. "If you leave him open in the fourth you're going to hear the groans from the crowd like tonight."
Dwyane Wade scored 20 points, Battier had 17 and Allen had 15.
James had 11 assists and six rebounds but could not extend his franchise-record streak of seven straight games with at least 30 points.
Miami trailed 73-63 entering the final period.
"We don't win games in 12, 24 minutes, 36 minutes," James said. "We've got to take 48 minutes. It was a good test for us coming out of the break.
"It took us a little while to get into our offensive rhythm."
Al Horford led the Hawks with 27 points and nine rebounds. Kyle Korver had 12 points, all on 3-pointers.
Josh Smith had 10 points, nine rebounds and a season-high nine assists in what could be his final game with the Hawks. Smith has been one of the league's most prominent names in reports leading to Thursday's 3 p.m. trade deadline.
"If it is his last game, he leaves a good mark," James said. "He played hard for this team."
Facing a large group of reporters at his locker after the game, Smith said he'll be relieved when the deadline passes.
"If I'm here or not, I'm going to still play hard," Smith said. "This organization has given me so much. They gave me a chance to play my dream. We'll have to wait and see what happens.
"I understand it's a business and whatever happens, happens. No love lost. If I'm still here, I'm going to compete and fight for a playoff position."
The Heat are 3-0 against the Hawks this season and have won six straight in the series.
Hawks coach Larry Drew said his team "just had too many breakdowns" on defense, including against Battier and Allen.
"It was the two bench guys who really put the nail in the coffin against us," Drew said.