Forbes just released its annual "top-10 highest-paid athletes in the world" list ... and LBJ came in second place, just behind Lionel Messi, who the outlet reports garnered around $130 million.

Forbes says LBJ's cash flow was obviously inflated by his huge Lakers contract -- but his ventures with the new 'Space Jam' flick, his "The Shop: Uninterrupted" talk show, and other endorsement deals pushed him over the $100 million mark, which is quite the feat.

According to the outlet, James is only the 10th athlete ever to earn more than $100 mil in a 12-month span ... and his $121,000,000 figure marks the most ever earned by an NBA player in a year (he previously held the record with $96.5 mil).

Outside of Messi and Bron -- a whole bunch of soccer players and basketball players rounded out the top 10, with Cristiano Ronaldo (#3, $115 million), Neymar (#4, $95 million), Stephen Curry (#5, $92.8 million), Kevin Durant (#6, $92.1 million) and Giannis Antetokounmpo (#10, $80.9 million) making the cut.

The others in the top 10 ... Roger Federer (#7, $90.7 million), Canelo Alvarez (#8, $90 million), and Tom Brady (#9, $83.9 million).

What's interesting ... Conor McGregor for the first time in a long time didn't crack the top 10 -- but don't fret, Forbes says he was close, landing somewhere in the top 50.

As for the 10 dudes at the top of the heap ... Forbes says in total, they all earned a combined $992 million in the last year.