Los Angeles Lakers superstar LeBron James congratulated Kansas City Chiefs quarterback and reigning NFL MVP Patrick Mahomes on his record-setting contract extension.

Mahomes will remain in Kansas City through the 2031 season after signing a mammoth new deal reportedly worth up to $503million, including $477m in guaranteed mechanisms.

The contract is the largest in North American professional sports history, surpassing the 12-year, $426.5m deal Mike Trout signed with MLB franchise the Los Angeles Angels in 2019. 

Mahomes – the 2018 NFL MVP – had two years remaining on the rookie contract he signed after being taken by Kansas City with the 10th overall pick of the 2017 draft. 

James, who has won three NBA championships and four MVP awards, used social media to congratulate the 24-year-old star.

"Congrats brother!!!! Let me borrow $5," James wrote in an Instagram story on Monday.

After sitting behind veteran Alex Smith as a rookie in 2017, Mahomes took the NFL by storm the following year in his first season as a starter.

The Texas Tech product threw for 5,097 yards and 50 touchdowns, tied for the second-most in a single season in league history, while leading the Chiefs to a 12-4 record and earning NFL MVP honours. He joined Peyton Manning (2013) as the only players with 5,000 passing yards and 50 touchdown passes in a season.  

Mahomes followed up by leading the Chiefs to their first NFL championship in 50 years with a 31-20 come-from-behind victory over the San Francisco 49ers in Super Bowl LIV in February.

The 24-year-old threw two touchdown passes in the fourth quarter as Kansas City scored 21 unanswered points to overturn a 20-10 deficit, and was selected as the youngest MVP in Super Bowl history. 

Mahomes, who is 24-7 as a starter in regular-season games and 4-1 in the postseason, currently owns league records for passer rating (108.9) and passing yards per game (302.4) among quarterbacks with at least 25 career starts.