Post Malone Finally Plays 'White Iverson' for Allen Iverson

It's been YEARS in the making ... rap star Post Malone finally got to meet Allen Iverson -- while playing his smash hit "White Iverson."

A.I. really came to life during the lyric, "F*ck practice."

The two met up during a night out in L.A. -- judging by the video, the two had been partying pretty hard before the song played.

Post had been DREAMING about meeting the NBA superstar for a while -- and previously told TMZ Sports how much he loved the guy.

Congrats Post ... dreams do come true (especially when you're rich and famous!)