03 Greedo Proposes To Girlfriend at Concert Before 20-Year Prison Stint

Rapper 03 Greedo ain't waiting 20 years to propose to his longtime girlfriend -- he popped the question at his concert Monday night ... right before starting a 20-year prison sentence.

Greedo gave his final performance, for now, to a packed house at L.A.'s Belasco Theater and got down on bended knee while performing his hit, "If I." Great moment -- his gf, Kei Bradley, said "yes," and the crowd had a pretty epic reaction.

Travis Barker, DJ Carisma and Asian Doll were all there supporting Greedo at the event held by Mike Rebel and Praying Man Productions. The feel-good vibes almost made you forget Greedo starts his prison bid in less than 48 hours.

It's really the ultimate bittersweet moment -- he pled guilty to possession of more than 400 grams of methamphetamine and unlawful possession of a firearm this year. Greedo plans to continue releasing music from the slammer.

Side note: Kei seems pretty ride or die. Mazel to the happy couple!