Justin Bieber
After the Biebs started posting videos to YouTube, he was discovered by his now manager Scooter Braun, who would introduce the singer to Usher. The rest is history.
Kate Upton
Yup! Kate Upton was struggling with making it big until her friend posted a video of her on YouTube doing the "dougie" and it went viral, gaining her almsot 200,000 Twitter followers, and a whole lot of attention!
Darren Criss
He founded a YouTube channel, StarKidPotter, with theatre friends from the University of Michigan and went on to become a big star, commonly known for his role on Glee.
Colbie Caillat
The Grammy Award-winning singer has since collaborated with the likes of Jason Mraz and Taylor Swift, but she was initially discovered through her YouTube videos on her MySpace profile.
Sophia Grace and Rosie
Sophia Grace and her cousin Rosie have been featured several times on The Ellen DeGeneres Show! The pair, who hail from England, rose to fame when a video of them performing Nicki Minaj's "Super Bass" took YouTube by storm!
Cody Simpson
Cody Simpson was discovered when he was just 12-years-old by record producer Shawn Campbell after viewing videos on the singer's YouTube channel.
Sean Kingston
The "Beautiful Girls" singer was discovered online and signed to Beluga Heights Records in 2007.
Soulja Boy
To promote what would eventually become his first hit, "Crank That," Soulja Boy created YouTube and MySpace accounts, which eventually led to his signing by Interscope Records in June 2007. That song also earned him a Grammy nod, not too shabby.
Lily Allen
Even though her father is musician Keith Allen, Lily had to use MySpace and YouTube to promote herself and gain the fans she now has.
Tyler Oakley
The YouTube star has gained huge fame from his hilarious videos! To date he has 6,696,673 subscribers on YouTube and has gone on to host events and appear as a special guest on various shows!
Karmin
After multiple YouTube hits, Karmin went on to get a record deal and #1 single, "Brokenhearted." So amazing!
Greyson Chance
After the 14-year-old uploaded a video of himself singing Lady Gaga's "Paparazzi," the clip was picked up by RyanSeacrest.com, TVGuide, The Huffington Post, and Yahoo! Music's video blog, Video Ga Ga. The buzz landed him a guest spot on The Ellen Degeneres Show and eventually got him signed to Interscope Records.