The 37-year-old's management agency, Klutch Sports Group, said the two-year extension was worth 97.1million dollars (£80.6million).
In a post on Twitter, Klutch's official account said: "Congrats @KingJames on your 2 year 97.1M dollar extension and becoming the highest paid player in the history of the NBA!"
The extension will take James's career guaranteed earnings past Brooklyn Nets forward Kevin Durant to 532million dollars (£441.6million).
James joined the Lakers from the Cleveland Cavaliers in 2018.
He secured his fourth championship with the Lakers' NBA Finals victory over the Miami Heat in 2020.