Pop star Justin Bieber is reportedly buying the $10.8 million mansion Ashton Kutcher has been renting out in the Hollywood Hills as an 18th birthday present for himself.

Kutcher has been renting the five-bedroom house, originally built for fashion executive Arif Noor and designed by Jeffrey and Rochelle Mills, for $50,000 a month since his December breakup with actress Demi Moore.

It boasts eight bathrooms, a gym, a home theater, a sauna, and an infinity pool, as well as retractable glass walls and its own elevator. The mansion spans 9,400 square feet.

But Bieber's new house isn't the only lavish gift the 18-year-old got for his birthday.

Manager Scooter Braun surprised Bieber on The Ellen DeGeneres Show last week by giving him a 2012 Fisker Karma electric car.

You work really, really hard, Scooter said before presenting the gift.

I always yell at you, 'don't get anything flashy.' You know, we're not about that. Be humble, be humble...and I kind of broke my own rule.

Bieber is expected to move into the $10.8 million mansion in the coming months. Seeing how close he was with girlfriend Selena Gomez at his 18th birthday bash, there are many who assume the Disney starlet will be moving in with him soon. In a recent interview, however, Bieber has said that he wouldn't move in with Gomez until they're married.

I don’t know. I feel like if it happens, it happens,” he told Life & Style at Dolce & Gabbana’s Fashion’s Night Out event, adding that he probably wouldn't live with anyone, even Gomez, until after marriage.

“Right now I’m just focusing on my music, and I feel like it’s going pretty well. I definitely believe in marriage--but not any time soon.”

Check out photos from inside Bieber's future home by clicking here.