James finished with a season-high 51 points in his first game at AmericanAirlines Arena as a member of the Lakers. The Lakers never trailed the Heat and led by as many as 21 points during the blowout.
"I've already been pretty efficient with my game," James said. "I don't like taking uncharacteristic shots or bad shots. My teammates look toward me to go out there and lead them to victory and I was able to do that tonight."
The win was James' first in Miami since he left the team in 2014 to rejoin the Cleveland Cavaliers.
The four-time NBA MVP was hitting shots from everywhere, including 6-of-8 attempts from 3-point range. He also pulled down eight rebounds and had three assists for the Lakers.
Los Angeles used James' prolific start to secure a 34-21 advantage in the first quarter. The Heat cut the lead to six points in the second frame, but still trailed 67-52 at halftime.
James posted 14 points in the third quarter, propelling the Lakers to a 92-76 advantage entering the final frame. The Heat worked to get within striking distance of its West Coast foes, but couldn't close the gap down the stretch.
Wayne Ellington led the Heat with 19 points. Kentavious Caldwell-Pope also chipped in 19 points for the Lakers.
"It was a special night," Lakers coach Luke Walton said. "From the jump ball he was in attack mode. He was making shots ... when players are as good as LeBron and they are having a night, it just looks easy. It's not easy but they make it look easy because they are that good."
The Heat host the Brooklyn Nets at 7:30 p.m. on Tuesday in Miami.
"I've seen it before on our side, but there's no question when he's hitting the three like that," Heat coach Erik Spoelstra said of James. "It almost changes the equation a little bit, but that's on me because we should have been more aggressive to take the ball out of his hands."
The Lakers face the Cavaliers at 8 p.m. on Wednesday in Cleveland in another game against one of James' former squads.
"It's always great to be [in Miami]," James said. "To come back here and see a lot of familiar faces ... We had some not so good times. We had more great times. It's always a respect factor and a love for the people of Miami, especially the people that work here. We put in a lot of time."