LeBron James has made history by becoming the first active NBA player to reach billionaire status.

The 37-year-old Los Angeles Lakers star officially joined the three comma club, with his net worth bouncing above $US1.2 billion ($1.7 billion) in pretax earnings, according to Forbes.

James’ NBA salary from Cleveland Cavaliers, Miami Heat, and the Lakers has earned the four-time MVP $383 million in the past 19 seasons and raked upwards of $900 million from endorsements and other business ventures since entering the league in 2003, the magazine states.

Despite missing the NBA finals in a tumultuous season for his LA team, Lebron earned more than $121 million in the past year to capture his new billionaire title.

Forbes accredits James’ lucrative endorsement deals with Nike, Pepsi, AT&T and Walmart as big components of the four-time NBA champion’s off-court success.

It said James structured deals to include equity in those brands, giving him a “cut of the upside instead of a quick paycheck”.

In 2003, James first signed with Nike as an 18-year-old, turning down Adidas and Reebok in favour of a potential long-term partnership.

In 2015, he signed a lifetime agreement with the clothing giant, rumoured to be worth more than $1 billion.

A significant stake in movie studio SpringHill Entertainment, which helped produce Space Jam: A New Legacy, also helped James achieve the billionaire status he had long dreamed of.

“It’s my biggest milestone,” LeBron said in a 2014 interview with GQ magazine.

“Obviously. I want to maximise my business. And if I happen to get it, if I happen to be a billion-dollar athlete, ho. Hip hip hooray! Oh, my God, I’m gonna be excited.”

James’ mother, Gloria James, was 16 when she had LeBron, and he has previously said he has never met his father.

“We had pressures as far as where the hell we gonna sleep at,” he told the US’s 60 Minutes in 2009.

“You know, from night, day to day, night to night. How we gonna eat from day to day, night to night?”

Michael Jordan is the only other NBA star to have reached billionaire status. He reached it a decade after his playing career in 2014.