The 'Call My Name' hitmaker was also joined by Girls Aloud bandmates Nicola Roberts and Kimberley Walsh at a party at the XS Nightclub and Encore Beach Club where they were seen knocking back tequila shots to a DJ set by the Black Eyed Peas star.
All of the friends at the bash surprised Cheryl by donning masks with her face on, causing the singer to question her own identity.
She joked on twitter: ''Erm... few questions!! Who am I? Where am I?? Why am I?? What am I? @NicolaRoberts @KimberleyJWalsh (sic)''
She was also given a giant birthday cookie by her pals.
Cheryl - who last year used her birthday as a return to public life following her firing from the US version of 'The X Factor' - also thanked her fans for raising money for her charity foundation as a birthday present.
She wrote on twitter: ''I can not believed you have raised over Â£2000 for my Foundation !! That is sooo special to me ! You are so kind thoughtful and generous
''Best birthday gift EVER.. !! Thank you ... I love you sooo much !! #Youknowmesowell ! (sic)''