Lonzo Ball's has finally released his first rap single -- and it's a 2-and-a-half minute tribute to his 16-year-old brother, Melo

It's called "Melo Ball 1" -- portions of the song were used in the first promo spot for LaMelo Ball's new $395 shoes ... but now, the Lakers star has dropped the entire track.

He brags about how his family's "ready for war," how Melo is the youngest person on the planet to have his own signature shoe ... and how it's all part of his father's genius vision.

Here are some of the lyrics ... 

"See my lil brother, he just doin' him. You can check the ‘gram, he got a million fans. Got his brothers, he don’t need no friends. He swagged out, he a walking gem."

"On the ball, that's just what it is. I'm a king, lil bro a prince. Throwin' racks and you throwin' fits. How you hatin' and you bangin' this?"

"Melo Ball 1, youngest in the game. Only 16 in the Lam' and he switchin' lanes."

By the way, Zo has another brother ... LiAngelo ... just in case he forgot.