James scored 27 points, grabbed 11 rebounds and distributed 10 assists for the Heat, with Bosh adding 24 points and 13 boards in the dominating win.
Miami held the NBA champs to 40.5 percent shooting and blew out the Lakers on their home court in a Christmas Day matchup.
Dwyane Wade, who returned to the lineup after missing Thursday's win at Phoenix, added 18 points and six assists as the Heat won for the 14th time in 15 games.
They also snapped a five-game losing streak to the Lakers in Los Angeles.
Kobe Bryant was held to 6-of-16 shooting from the floor on his way to 17 points and Pau Gasol contributed 17 points and eight rebounds for Los Angeles in the setback.