The Duke of Edinburgh was hospitalised in Cambridge on Friday after falling ill with chest pains during a Royal Family gathering at the Sandringham Estate.
The 90-year-old initially underwent precautionary tests, upon which the blockage was discovered. He will now remain in hospital overnight.
A Buckingham Palace statement said: "Following tests at Papworth Cardiothoracic Hospital in Cambridge this evening, the Duke of Edinburgh was found to have a blocked coronary artery which had caused his chest pains.
"This was treated successfully by the minimally invasive procedure of coronary stenting. Prince Philip will remain in hospital under observation for a short period."
The Queen's husband was said by BBC News to have been in "strikingly good health" of late.
Prince Philip was previously treated for a serious chest infection in 2008.
Before the prince fell ill, the Royal Family had been enjoying their first Christmas retreat since the wedding of Prince William and Kate Middleton.
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