Luke Rockhold Ringside for Brutal Karate Combat K.O.

Luke Rockhold was one of the special VIP guests at a pretty crazy fight in Miami last night -- with supercars, celebrities ... and a brutal knockout.

Luke was ringside at Karate Combat: Inception -- where the fighters are driven to the ring in Rolls-Royces and then walk through a parking lot of supercars before actually fighting.

The guest list was invite only -- and Rockhold made the cut to watch Dionicio Gustavo take on Alexandre Bouderbane, a part-time fitness model.

Things turned brutal when Gustavo cracked Bouderbane with an overhand right -- sending the model crumpling to the ground.