Justin Bieber is all grown up. The Canadian pop singer celebrates his 18th birthday today. Here's a look back at the singing sensation's transformation from YouTube phenom to superstar.
Bieber attends Nickelodeon's Kids' Choice Awards in March 2009 with his mentor Usher.
The singer entertains crowds at Arthur Ashe Kids' Day, a U.S. Open event, in New York in August 2009.
Bieber performs at the Pepsi Super Bowl Fan Jam in Miami Beach in February 2010.
Complete with a letterman jacket and a drum solo, Bieber surprises fans in an outdoor performance at the MTV Video Music Awards in Los Angeles in September 2010.
Bieber, then 16, promotes "First Step 2 Forever: My Story" at a bookstore in New York in November 2010.
The pop idol attends the Los Angeles premiere of "Justin Bieber: Never Say Never" in February 2011. He's accompanied by Usher and manager Scooter Braun.
That same month, Bieber shows off on the basketball court at the 2011 BBVA NBA All-Star Celebrity Game in Los Angeles. Even former NBA player Scottie Pippen said he was surprised by Bieber's skills.
Madame Tussauds had everyone seeing double when Bieber's wax figure was unveiled in March 2011 in London.
Bieber attends the MTV Video Music Awards in August with a snake on one arm and girlfriend Selena Gomez on the other. He won the best male video award for "U Smile" that night.