Selena Gomez celebrated her 21st birthday a few days beforehand, throwing a huge bash in L.A. 

The Come & Get It singer celebrated at the Roosevelt Hotel with friends including 24-year-old actress Lily Collins. At the party, Gomez was surprised with a leopard-print cake, which had photos of her on the top and gold frosting.

Even though the girls could've taken a limo to the party, they opted to drive themselves. (Gomez was in the passenger seat while Collins took the wheel.)

The Mirror Mirror actress and Gomez were both dressed up in costumes to also celebrate Julianne Hough's flapper-themed birthday bash in LA. Gomez wore a short black dress, feather boa, a devil horn headband and very high heels. On the other hand, Collins was dressed in a flapper dress and wore a black turban around her head.

On Monday, Gomez celebrated her birthday with her fans by releasing her music video, Birthday. She wrote, "I wanted to celebrate my 21st Birthday with all of you, so we made this video for us all to celebrate to. Thank You for all the love and support you have shown and continue to show me. I love you all so much!!"

In the song, Selena sings, "Blow your dreams away with me...Tell them that it's my birthday when I party like that." The Spring Breakers star is seen dancing throughout the video with friends and throwing confetti in the air.

Birthday, available to purchase on Tuesday, is featured on Gomez's debut album Stars Dance, which was released on July 19.

As far as her birthday plans go, in May Gomez told MTV, "I'm going to have a huge party, so I'm excited. I'll have all of my friends. I don't really celebrate my birthday; I'll go to dinner with my friends."

No word yet on whether or not her on-again off-again boyfriend, Justin Bieber will be there.

"This is a big one," she added. "I think my friends are more excited than I am to be honest because they are older than me so they're like, 'Can we finally take you places?' And it's like, 'Well when I turn 21.'"

Watch Selena Gomez's Birthday video below.