Shane Battier scored 11 and Mario Chalmers finished with 10 for Miami. James was sent home from the team's shootaround practice earlier in the day to rest, and finished with eight rebounds and eight assists to go with 12 for 27 shooting.
Pau Gasol scored a season-high 26 for the Lakers, Kobe Bryant scored 24 and Andrew Bynum finished with 15 points and 12 rebounds.
Miami moved to 5-0 this season without Dwyane Wade, who missed his second straight game with a sprained right ankle. He missed three games earlier this season with left foot soreness.
Bryant put together a great late run to attempt a comeback, banking in a 3-pointer and following that seconds later with a steal and transition dunk that got the Lakers within 94-84 with 2 minutes left. But Derek Fisher's 3-point try on the next Los Angeles possession hit the front of the rim, Udonis Haslem controlled the rebound and James made a 15-foot runner to seal the outcome.
It was the first time James had gone against his former coach in Cleveland, Lakers' boss Mike Brown. At the Lakers' shootaround practice Thursday afternoon Brown said he and James had not spoken in advance of this game and didn't know if they would — but James made sure they did, running over to the Los Angeles bench and grabbing his former coach for a long embrace and a few words.
Brown was asked before the game if going against James would bring out sentimental memories of their time in Cleveland together.
"I had a great time coaching LeBron," Brown said. "I wouldn't be in this suit if it wasn't for him."
James showed no signs of illness. In fact, he apparently felt good enough to take on two teams — the Lakers ... and the Miami Marlins. James' momentum carried him over the sideline across from the Lakers' bench in the first half, nearly knocking over none other than Marlins owner Jeffrey Loria, who escaped the collision with the 265-pound two-time MVP unscathed.
Loria spent most of the next few minutes laughing.
Meanwhile, the Lakers had very little to laugh about.
They shot 31 per cent in the first half, their lowest output for any half this season. Bryant had as many field goals in the opening 24 minutes (one, on eight shots) as Heat forward Eddy Curry (1 for 1), who got his first NBA action since December 2009 when he checked in late in the first quarter for a 2 1/2-minute stint in which he made a basket, grabbed a rebound, was charged with a turnover and got a pair of loud ovations from a sellout crowd.
Curry returned for another stretch to start the fourth quarter, finishing his night with six points and three rebounds in six minutes. Curry said earlier Thursday that he lost about 65 pounds to get ready for his comeback, more than half of that since the start of Heat training camp in December.
"He gave us good minutes, good energy," Heat coach Erik Spoelstra said during a televised in-game interview. "He's done a lot to get to this point. We're all very proud of him."
Miami's lead was 52-37 at the half, buoyed by eight 3-pointers — more than the Heat attempted in two December games — and a sizzling defensive start where the Lakers were forced into missing 18 of their first 24 shots. Over a 51-minute stretch going back to late in the first half of Tuesday's game against San Antonio, the Heat had outscored the Spurs and Lakers by a whopping 137-83 margin.
There was no second-half let-up, either. James scored nine points and Bosh was 4 for 4 from the floor in the third quarter, and even with the Lakers shooting 56 per cent in the period Miami pushed its lead out to 77-56 entering the fourth.
NOTES: Bryant passed Bill Russell (40,726) for 21st on the league's all-time minutes played list. Next up: Michael Jordan (41,011). At his current pace, Bryant should become No. 5 on the NBA's career lists in points (passing Shaquille O'Neal) and free throws made (passing Jerry West) before the All-Star break. ... Ludacris was among the celebrities in the crowd. ... The Heat wore new all-black alternate uniforms, giving the Lakers the chance to wear their home gold on the road. ... Magic Johnson sat with Heat president Pat Riley for the second straight game. ... Gasol's previous season-best was 22. He hadn't scored 20 in any of his last nine games.