Atlanta had already clinched the Southeast Division title but they have now secured home court advantage throughout the Eastern Conference playoffs, with 19 days still left in the regular season.
DeMarre Carroll scored 24 points, 19 in the first half, and Paul Millsap had 21 on Friday for the Hawks, who have bounced back from a three-game losing streak to win two in a row.
Al Horford added 15 points for Atlanta and Dennis Schroder had 12 points and 11 assists, while Luol Deng led the Heat with 17 points.
Dwayne Wade returned from a knee injury and scored 13 points but Miami finished their four-game road trip 1-3 and were without Hassan Whiteside and Chris Andersen due to injury.
The Heat remained in seventh place in the Eastern Conference, one game ahead of the Boston Celtics, who occupy the eighth and final playoff spot.
Boston defeated the New York Knicks 96-92 on Friday to remain on course but Brooklyn Nets, Indiana Pacers and Charlotte Hornets are all within striking distance.
The Nets enhanced their chances with a crucial 106-98 win over LeBron James and the Cleveland Cavaliers in Brooklyn.
The Nets’ reserves out-scored their counterparts 54-20, led by Bojan Bogdanovic’s 18 points, while Jarrett Jack added 16 points and Alan Anderson scored 13.
Kyrie Irving led the Cavs with 26 points, James finishing with 24, nine assists and five steals.
Over in the Western Conference, Stephen Curry scored 38 points and Klay Thompson added 28 to lead the Golden State Warriors to a 107-84 victory over the Memphis Grizzlies, their eighth victory in a row.
Golden State (59-13) avenged a 105-98 loss to the Grizzlies (50-23) in December and Memphis were the only team this season the Warriors had not defeated.
Boris Diaw scored 19 points for the San Antonio Spurs, who beat the Dallas Mavericks 94-76 to split their four-game season series.
And James Harden recorded his league-leading 31st 30-point game while Josh Smith flirted with a triple-double as the Houston Rockets clinched a postseason berth with a 120-110 win over the Minnesota Timberwolves.
Harden finished with 33 points and eight assists for the Rockets (49-23), who closed to within a half-game of the Grizzlies for second in the West.
Friday???s NBA results:
Orlando 97-111 Detroit
Philadelphia 98-119 LA Clippers
Washington 110-107 Charlotte (OT)
Atlanta 99-86 Miami
Brooklyn 106-98 Cleveland
NY Knicks 92-96 Boston
Toronto 94-83 LA Lakers
Houston 120-110 Minnesota
Memphis 84-107 Golden State
New Orleans 102-88 Sacramento
San Antonio 94-76 Dallas
Denver 107-91 Utah
Phoenix 81-87 Portland