The billionaire had a fully lit weekend in Miami, owning the dance floor at LIV Nightclub. Witnesses tell us Bill showed up at around 11 PM Friday night ... flanked by his bodyguards. He had his own table (again, he's a billionaire) and was there with a small group of friends.

Check out the vid ... you can see Bill's muscle surrounding him while he puts in some serious work on the dance floor ... with club dancers in tow. They danced to Waka Flocka Flame's "Grove St. Party" and Nicki Minaj's "No Frauds" ... two classics.

Bill -- who was in Miami to watch his daughter compete in a prestigious equestrian tournament -- was spotted at Delano South Beach prior to hitting up LIV ... where they partied 'til around 1 AM.

BTW ... seems Bill's dance moves haven't evolved since he launched Windows 95!!!