It is the second time heir to the throne Charles, 73, has contracted coronavirus, after he fell ill with the virus in 2020.
A message on the prince’s official Twitter page read: “This morning The Prince of Wales has tested positive for COVID-19 and is now self-isolating.
“HRH is deeply disappointed not to be able to attend today’s events in Winchester and will look to reschedule his visit as soon as possible.”
The development comes just days after the Queen marked her Platinum Jubilee by expressing her “sincere wish” that the Duchess of Cornwall would be Queen Camilla at Charles’s side when he is one day King.
On Wednesday evening, Charles met scores of people and was accompanied by Camilla at a reception in the British Museum to celebrate the work of the British Asian Trust (BAT).
The duchess meanwhile carried on with her engagements on Thursday, visiting Paddington Haven, a sexual assault referral centre in West London, where she met former Love Island star Zara McDermott and discussed her experience of revenge porn and assault.
At the British Asian Trust reception, Charles spoke about the “devastating impact” the pandemic has had on south Asia.
Charles was in close contact with Chancellor Rishi Sunak, Home Secretary Priti Patel and former Liverpool footballer Ian Rush.
In March 2020, the prince caught Covid-19. He suffered a mild form of the virus and described how he lost his sense of taste and smell.