Floyd Mayweather Does Karaoke With Kanye, Aaron Donald, Antonio Brown For Birthday

Floyd Mayweather sang his damn heart out to celebrate his 45th birthday ... and he called on Kanye West, Aaron Donald and Antonio Brown to be his backup singers!!

TMZ Sports has learned -- TBE hosted a private party at David Grutman's Sushi Fly Chicken in Miami on Wednesday to celebrate his big day ... and the karaoke machine was getting put to good use.

The 50-0 boxing legend donned a baby blue plaid blazer and pants for the rager ... and he was certainly in great spirits -- dancing with a huge smile on his face.

The whole room was getting in on the fun -- singing along as Donell Jones' "Where I Wanna Be" blasted over the speakers.

But, the most surprising performance of the night?? AD and his wife, Erica, rapping along to "Set It Off" by Boosie Badazz -- and Floyd was loving every second of it.

The party then made it to Gold Rush Cabaret strip club ... where Floyd was honored with cutouts and signs -- including a shot of him beating up on Conor McGregor during their fight in 2017.