Big Willie Style was in full effect after Will Smith won an Oscar and slapped Chris Rock on live TV … Will was dancing to his famous hit and holding his award at an after-party.

Ya gotta see this video of Will on Oscar Sunday … no, not the one where he slaps Chris for joking about Jada Pinkett Smith … this one, where he’s dancing to his song, “Gettin’ Jiggy Wit It,” at the Vanity Fair Oscars after-party in Hollywood.

There’s a huge circle around Will, and a ton of cameras in his face … and it certainly doesn’t look like he’s bothered by what went down on stage with Chris … cutting loose on the dance floor, singing his own lyrics and showing off his Oscar for his work in “King Richard.”