Choosing a 70s disco theme for her celebrations at Box nightclub in Soho, Rita made sure she turned 23 with a bang!
Last night (26 November), she wore a platinum blonde wig with plenty of backcomb, while her bright red dress showed off lots of flesh... Just as well boyfriend Calvin Harris was there by her side to protect her from unwanted admirers!
The unusual outfit had a hood which Rita popped up as she arrived at the famous celeb hangout.
During the evening, Rita posed for a picture with her friend and stylist Kyle De'volle and shared it with her Twitter followers.
She captioned the photo: "Studio 54....70's The ORA and Devolle way @kyledevolle #itsmyBirthday."
Rita partied until 4am when she headed home with beau Calvin.
As well as singer Calvin - who arrived with a bag of cupcakes for the birthday girl - her friends on the night included Eve, Mutya Buena, Kelly Brook and Rizzle Kicks' Jordan Stephens.
But sadly no one else embraced the fancy dress theme! Spoilsports!
While flame-haired Eve looked gorgeous in a black cape with matching accessories, there was sadly not even a nod to fancy dress.
And Kelly Brook looked like she was about to attend a more formal function in a black and gold dress with matching fitted jacket.
Earlier in the day, Rita had posted a provocative selfie of herself apparently topless on Instagram, with the message: "Birthday girl!! Today I'm allowed to be A F***ING STAR! Thank you everyone for the birthday wishes and I love you!!!!"
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Watch the video for Rita Ora's single 'How We Do (Party)':