The former GMTV host shared her symptoms in a Twitter post on Friday evening.
She explained: “I am in bed with #coronvirusuk It’s not a very pleasant bedfellow, but nothing more than sore throat, dry cough, headache & tiredness.”
Fiona added: “As long as it stays that way....DON’T panic!”
One fan then tweeted Fiona asking how long she’d been “suffering”, to which the star responded: “I’m not suffering. It’s fine. Thanks for asking.”
Fiona is the latest star to reveal that she has coronavirus, with Tom Hanks and Rita Wilson the first high-profile names to share the news that they had tested positive.
They both received treatment for Covid-19 in hospital in Australia, and said earlier this week that they had since entered self-isolation.
Since then, Idris Elba has also gone public with his diagnosis, claiming he was inspired to share his diagnosis by the Oscar-winning star.
“I’m really proud of Tom Hanks, who is also someone in the public eye, who came out and said they have it and been public about it,” Idris said in a live-stream Q&A on Twitter. “I was definitely motivated by Tom’s move there.”