Selena Gomez's Birthday: Singer Celebrates With Justin Bieber at Teen Choice Awards 2012

Singer Selena Gomez celebrated her 20th birthday by attending the Teen Choice Awards 2012 with her boyfriend, pop star Justin Bieber.

The former Disney star sat in the front row with the 18 year-old Canadian at the Gibson Amphitheatre in Universal City, California, wearing a pink dress by Dsquared2 with Herve Leger sandals.

Like Us on Facebook

The highlight of the night for Gomez was when she went on stage to accept her surfboard award from comedian Kevin Hart, he surprised her with cupcakes decorated with sparklers on top. Hart, who presented the award with "Vampire Diaries" star Nina Dobrev, then asked the audience to sing "Happy Birthday" to her. Gomez became embarrassed and yelled "Oh no!" and put her face in her hands as Hart asked everyone to sing along with him.

The television cameras showed Taylor Swift and Disney star Miranda Cosgrove singing with the audience as well.

Gomez tried to blow out the sparklers but had no success. She pushed the cart out that carried her sparkler-topped cupcakes off the stage and quickly ran back to her seat in the front row with Justin Bieber.

Bieber, 18, later performed his song "Boyfriend" and latest single, "As Long As You Love Me" with rapper Big Sean.

While Gomez wore her hair straight to the award show, she had shared a photo of her birthday look on Facebook, which saw her hair styled wavy with a French braid.

The Teen Choice Awards are voted by teen viewers online and gives actors, musicians and other artists who are popular with kids the chance to thank their fans. The trophies are a life-size surfboard and are given in numerous categories spanning film, television and music, as well as unconventional awards.

The two-hour awards show was hosted by former Disney Channel actress and current "X Factor: USA" judge Demi Lovato and "Glee" star Kevin McHale.