James said this week he would not discount the possibility of returning to play for Cleveland one day, but those comments did not make the reception he received in his former home any less noisy.
James, who left Cleveland in 2010 to play for Miami, was booed every time he touched the ball. He made 11-of-19 shots from the field and sent the Heat racing to a 21-5 lead.
It was Miami's fifth straight victory, all of those wins coming on the road. The Heat closed out a 5-1 trip and will now play three in a row at home.
Dwyane Wade added 22 points while Chris Bosh had 16 points and 12 rebounds for Miami. The Heat shot 50 percent from the field and made 14-of-21 shots from 3-point range.
Cleveland, which lost for the third time in four games, got 17 points from rookie Kyrie Irving.