Spoelstra passed Pat Riley to break the record. Spoelstra is only one of two active head coaches in the NBA to post at least 450 wins with their current team, joining San Antonio's Gregg Popovich, who has 1,169 wins with the Spurs.
Spoelstra saluted Riley, whom he called his mentor, after the Heat grinded out the victory, despite shooting just 37.8 percent from the field.
"I thought that it would be most fitting to go retro and have an old-school Miami Heat game in honor of coach Riley," Spoelstra said. "This is the type of game he probably enjoys the most -- you win shooting 37 percent. I think we scored too many points this game. But those are the old-school, tough, grind-it-out, find any way as a competitor to win the games. That's in honor of my mentor and my coach. He's still my coach."
Spoelstra, whose career record now stands at 455-296 in 10 seasons, guided the Heat to four straight NBA Finals from 2011-14, winning the title in 2012 and 2013.
The Associated Press contributed to this report.