Rita Ora, 28, was due to perform at a free Amazon event in Berlin, Germany this evening.
In view of her 15 million Instagram followers, she said she can no longer make the show and will be replaced by Liam Payne, 26.
As part of a lengthy statement, she wrote: “I am so sad to have to announce that I’ve woken up today poorly and have been ordered by doctors to miss the amazon event today.
“I’ve been looking forward to seeing you all so much.
“It is a decision that has been taken out of my hands and I am so sorry not to be there.
The I Will Never Let You Down singer added: “Nothing makes me happier than performing and seeing my incredible fans and not being able to do that is devastating.”
Express.co.uk has contacted a representative for Rita Ora for comment.
Rita followed her up post informing fans ex One Direction will be making an appearance at the event instead.
“Silver lining, my amazing friend @liampayne is going to step in for me and meet you all! Please give him some big Berlin love!”
Earlier this week, Rita Ora flashed more than she hoped during a gig in London on Monday.
The singer accidentally flashed her underwear as she sported a show-stopping red outfit.
Rita’s risqué number featured cut-out detail and a daring thigh-high slit.
The former X Factor judge also accompanied her look with a red hat, which partially covered her face, and a pair of knee-high boots.
Unfortunately for the star, her daring outfit parted at the front, giving viewers a glimpse of her underwear as she strolled along a street.
Rita experienced the mishap as she left the Chiltern Firehouse at the Cartier London Celebration.
Seemingly unfazed by her wardrobe malfunction, she smiled for cameras as she held on to her dress.
Also this month, the singer was spotted filming scenes for a new Sky Cinema project.
The singer-turned-actress will play the Artful Dodger in the modern version of Oliver! alongside Jude Law’s son Rafferty, 23, who will play Oliver Twist.
Rita was pictured in a short blonde wig as she sported police uniform in the capital city.
The Girls hitmaker previously appeared alongside Dakota Johnson in the movie Fifty Shades of Grey and it’s two sequels.