LeBron James finished with 29 points, nine assists and eight rebounds, while Dwyane Wade contributed 21 points to help the Eastern Conference-leading Heat tie a franchise-best 25-game start (19-6).
Kevin Durant poured in a game-high 33 points for the Thunder but was unable to prevent his team from suffering a fifth straight loss against Miami.
Oklahoma later surrendered top spot in the Western Conference to the Los Angeles Clippers, who stretched their franchise-record winning streak to 14 games with a 112-100 triumph over the Denver Nuggets thanks to 22 points from Jamal Crawford and 20 from Matt Barnes.
Elsewhere on Christmas Day, Kobe Bryant inspired the Los Angeles Lakers to a 100-94 comeback victory over the New York Knicks at Staples Center.
Bryant scored 34 points as the Lakers, who trailed 78-77 heading into the final quarter, posted a season-high fifth consecutive win. Carmelo Anthony matched Bryant's points haul in a losing cause for New York.
Boston overcame the Brooklyn Nets 93-76, Rajon Rondo leading the Celtics with 19 points at Barclays Center.
James Harden led five Houston players in double figures with a 26-point contribution as the Rockets eased past the Chicago Bulls 120-97 at the United Center.