Guccie Mane proposes to his girlfriend at a basketball game

Gucci Mane dominated the NBA Kiss Cam Tuesday night at the Atlanta Hawks game -- proposing to his GF with a diamond the size of a fist ... and the crowd went wild!!!

The lucky lady is Keyshia Ka'oir -- who first met Gucci on the set of one of his music videos in 2010.

The couple was sitting courtside when the kiss cam began to roll -- and though Gucci never got down on his knee, Keyshia didn't seem to mind once she saw that rock!!

Watch the proposal below