He tweeted following the gig: "Great show!!! Now gonna go celebrate 19!! Thanks."
The pop star returned to his London hotel around 3 a.m. and partied with rumored girlfriend Ella-Paige Roberts-Clark and other beautiful girls. Despite the cold tempertaures, Bieber arrived at his hotel without a shirt on, showing off his six-pack and wearing low-hanging pants that revealed quite a bit of his tighty whities.
Part of the night's festivities included going to members-only after-hours club, BLC. Bieber and his entourage left at 5 a.m. and headed to London's Edgware Road where they ate kebabs in a Lebanese restaurant, according to the Daily Mail.
Check out more photos of Justin on his birthday...