Cardi B twerked like her life depended on it at HOT 97's Hot for the Holidays concert on Thursday -- and got rewarded for her efforts with a Colin Kaepernick meet-and-greet after the show!
You might've heard ... Cardi's been backing Kaep ever since she blew up with "Bodak Yellow" -- saying she was gonna boycott the NFL if no team signed him back in September.
Fast-forward a few months ... and the hip-hop star finally got to meet her favorite football player and his GF, Nessa -- a HOT 97 radio host -- backstage at the Prudential Center.