Teenage heartthrob Justin Bieber is on cloud nine these days as his 4 million albums have been sold worldwide in less than a year.

Bieber's Madison Square Garden has also been sold out.

Bieber has now sold 3.2 million copies of his 'My World' (released last November) and 'My World 2.0' (March) in the US, plus 7.7 million songs digitally downloaded, according to Nielsen SoundScan.

"Madison Square Garden was a big milestone. Justin is a kid who grew up in public housing with a single mom. He always said selling out the Garden was his dream," the New York Post quoted his manager, Scooter Braun, as saying.

Bieber's also been shooting a movie of his life story, and celebrities -- including Miley Cyrus, Usher, Snoop Dogg and Adrian Grenier, who all attended his MSG show-will appear in the film due out in February.

"It's a real rags-to-riches story, and shows where Justin came from and the hard work that got him to where he is now," added Braun. (ANI)