TMZ Sports broke the story ... the 41-year-old, 2-time NBA champion has inked a deal with Celebrity Boxing to step into the ring this summer at the Showboat Casino in Atlantic City, NJ.

While LO's opponent hasn't been announced (yet), it hasn't stalled the dude's preparations ... teaming up with big-time trainer Xavier Biggs to help him prep for the fight.

In the footage -- obtained by TMZ Sports -- Odom is seen working on his jabs ... which may seem like standard workout stuff ... until you hear the sound he makes when his gloves hit the mitts.

FYI -- Biggs is the go-to guy for stars like Kevin Hart and Usher ... so whoever's going against the former Laker has their work cut out for them. After all, have you SEEN Kevin Hart lately?!

Of course, Odom is the first NBAer to take the ring since Nate Robinson got knocked out by YouTuber Jake Paul ... and we're assuming he's hoping it ends up better for the hooper this time around.

While Celebrity Boxing's Damon Feldman has yet to make Odom's opponent official, we're getting word it's a MAJOR household name ... but who knows, after seeing this footage??