Here it is ... the first footage from INSIDE Serena Williams' awesome New Orleans wedding -- with incredible dresses, the Cupid Shuffle ... and Venus Williams gettin' down to "Back That Ass Up!"
The party looked like a blast -- guests drinking and dancing while the DJ turned the party up!
Serena looked beautiful -- sporting a short princess style cocktail dress with white sparkly Nike shoes so she could dance comfortably.
Venus also looked smokin' hot in a tight fitting lace cocktail dress of her own.
We're told everyone had a GREAT time -- and the food was an absolute hit!!
One partygoer tells us there was a Cajun section, seafood section, a "Tour of Italy" section with all sorts of pasta ... a steak section with different cuts of meat and a traditional American section.
Who's hungry now!?!?