Watch out, world...Justin Bieber turns 21 today!

The day has finally come.

It's March 1, and this year it marks Justin Bieber's 21st birthday.

And we all know what that means.

So does the Biebs, and he's VERY excited about it.

THE PARTY GOT STARTED LAST NIGHT WHEN HE BEGAN HIS BIRTHDAY COUNTDOWN:

THEN, SHORTLY BEFORE MIDNIGHT, THE CELEBRATING REALLY KICKED INTO HIGH GEAR. CLICK ON THE LINK IN HIS TWEET TO SEE BIEBER DANCE AROUND WITH CHAMPAGNE BOTTLES TO 50 CENT'S IN DA CLUB:

AND DON'T FORGET: JUSTIN LOVES YOU.

HERE'S HOPING THE LOVEFEST CONTINUES.