Kim Kardashian and Mike Tyson were among the guests at Justin Bieber's surprise birthday party on Friday (02.03.12).

The 'Baby' hitmaker turned 18 on Thursday (01.03.12) and celebrated reaching the milestone age at a bash thrown by his manager Scooter Braun and mother Patti Mallette at the Beverly Wilshire Hotel, where guests also included his girlfriend Selena Gomez - who jetted in from Florida, where she has been filming 'Spring Breakers', for the occasion - Kylie and Kendall Jenner and Ashley Tisdale.

One partygoer said: ''Everyone danced all night.''

Many of Justin's childhood friends flew in from Canada for the occasion, as did his grandparents, but onlookers say he spent most of the night with Selena.

The source added to UsMagazine.com: ''He was all over Selena the whole time, walking her around by the hand. He kept kissing her. It's clear she was the best part of the night for him. He is so in love with her.''

Justin previously said he was planning a ''low key'' birthday Celebration.

He said: ''My birthday, I'm going to hang out with my friends and family, have a little get-together; nothing too crazy.''

The Canadian singer was given an eco-friendly luxury Fisker Karma sports car by his manager Scooter Braun during an appearance on the 'Ellen Degeneres Show' last week but he was most impressed by a different gift.

Asked what his best present was, he said: ''I got a pool table, a purple one and it's amazing. That's probably my favorite.''