Clarkson is a rising star after two seasons with the Lakers, who acquired the 46th overall pick from Washington on draft night in 2014. The Missouri product has been a steady scorer and a rare bright spot on the two worst teams in Lakers history.
The Vertical first reported the agreement.
After averaging 11.9 points per game and making the NBA's All-Rookie team in the 2014-15 season, Clarkson boosted his production to 15.5 points per game last season, second on the team behind Kobe Bryant.
Clarkson started 79 games last season, teaming up with D'Angelo Russell in the Lakers' intriguing young backcourt. Although they didn't win many games, they showed more than enough promise for the Lakers to keep them together in the core of a young roster that also includes forwards Julius Randle and Larry Nance Jr. along with Brandon Ingram, the No. 2 overall pick in last month's draft.
The smooth-shooting San Antonio native added 4.0 rebounds and 2.4 assists per game to his scoring output while playing a team-high 32.3 minutes per game. He also capably handled a transition to shooting guard after largely playing as a point guard during his rookie season.
The Lakers extended a qualifying offer to Clarkson on Thursday, making him a restricted free agent and allowing them to match any offer made by another team. Clarkson had repeatedly said he didn't intend to leave the Lakers, considering his new contract a formality.
After finishing a franchise-worst 17-65 last season, the Lakers are moving quickly to use their estimated $55 million in salary-cap room during the opening hours of free agency.
Los Angeles also made qualifying offers to Tarik Black and Marcelo Huertas.
Information from The Associated Press was used in this report.