James purchased an undisclosed amount of shares belonging to the Fenway Sports Group (FSG,) which also owns English Premier League football champions Liverpool.
LeBron James has reportedly added ownership stakes in baseball's Boston Red Sox and a US stock car race team to England football champions Liverpool in his sports empire.
The 36-year-old Los Angeles Lakers forward purchased an undisclosed number of shares in FSG, which has also approved a $750 million private investment from RedBird Capital Partners, the Boston Globe reported, citing a source with knowledge of the deal.
FSG, which also owns English Premier League soccer champions Liverpool, did not respond to a request for comment.
James had already owned a 2 percent stake in Liverpool since 2011.
The 17-time NBA All-Star is perhaps an unlikely figure to join the Boston sports landscape, with allegiances to some of the city's fiercest rivals.
James, who picked up his fourth NBA title last year, has previously rooted for MLB's New York Yankees.
The Red Sox finished the 2020 season bottom of the AL East with a 24-36 record.