Justin Bieber will be in good company on his 18th birthday tomorrow. He's celebrating with an appearance on Ryan Seacrest's show with his pal and newly signed artist, Carly Rae Jepsen! Seacrest announced the visit from the Canadian crooners on Twitter:

"Gonna have @justinbieber & @carlyraejepsen on @OnAirWithRyan thursday (it's his birthday...what should I get him?)"

Bieber has been promoting Jepsen since before she even signed with his label. In January, Bieber's galpal, Selena Gomez, tweeted a photo of a cheesin' Biebs with the caption, “This smile is because of Carly Rae Jepsen.. We have not stopped listening your song girl!”

Since then, Bieber has been blowing Jepsen up in a big way. When she announced on MuchMusic that she was working with Scooter Braun, Biebs called in to surprise her and gave the deets on why he was so passionate about working with her. “I teamed up with Scooter Braun and Jimmy Iovine,” Bieber said. “When I was in Canada, I heard a song on the radio called ‘Call Me Maybe,’ and I thought it was a smash,” Bieber continued. “I want everyone to know we signed her so everyone can check her out. She’s gonna blow up.” Biebs, Gomez and some famous pals even made a silly video for 'Call Me Maybe.'

Following his stint with Seacrest, Bieber does plan on celebrating -- but don't expect a bender or blow out party. In tune with his grounded nature (which, we should point out, is especially unusual for a star of his magnitude), Bieber is having a small, quiet celebration with family and friends in Los Angeles. Sounds like a happy birthday to us -- and to the cougars who are happy he's not jailbait anymore!