The extension removes the possibility of James entering free agency next summer. His previous contract had a player option for 2021-22 at $41 million.
James turns 36 on Dec. 30, and the new deal extends through the 2022-23 campaign - what would be his 20th season in the NBA - and his 38th birthday.
He is on pace to pass Kareem Abdul-Jabbar as the NBA's all-time leading scorer sometime during the 2022-23 season.
His oldest son, Bronny, is on track to graduate high school in 2023. Currently ranked No. 24 in that year's ESPN 100, the junior James could go straight to the NBA if the league changes its longstanding prep-to-pro rule by then.
The Lakers still have not agreed to terms with Anthony Davis on a new contract, although that is perceived as a formality and is expected to happen in the next week.