James came close to a triple-double with 33 points, nine assists and nine rebounds and Anthony Davis sank 14 of his first 15 shots en route to 32 points to move the Lakers halfway to their first championship since 2010.
The Lakers -- wearing the Kobe Bryant-inspired "Black Mamba" uniforms -- shot 51% from the field and took a season-high 47 3-pointers to counter the Heat's zone defense. Los Angeles improved to 4-0 in the postseason when wearing the all-black uniforms, one of the many tributes to the Lakers legend who died in a January helicopter crash.
"This is what it's all about," James said. "We're thinking about the Bryant family ... and hopefully we're making them proud."
Jimmy Butler finished with 25 points, 13 assists and eight rebounds for the Heat, who were playing without injured starters Bam Adebayo and Goran Dragic. In Adebayo's place, Kelly Olynyk had 24 points on 9-of-16 shooting. Rookie guard Kendrick Nunn absorbed a majority of Dragic's minutes and had 13 points.
Heat guard Tyler Herro recorded 17 points and seven rebounds, while Jae Crowder notched 12 points and seven boards. Miami got within nine points in the fourth quarter but couldn't close the gap any further.
Game 3 of the best-of-seven series is set for Sunday night.