He was taken from the royal couple's Sandringham country estate to hospital in Cambridge where an "invasive procedure of coronary stenting" was performed, the palace said.
Philip, the Duke of Edinburgh and father of Crown Prince Charles, was taken to the cardiothoracic unit at Papworth Hospital after he complained of chest pains.
The blocked artery was "treated successfully by the minimally invasive procedure of coronary stenting," a palace spokesman said. "Prince Philip will remain in hospital under observation for a short period."
It was the most serious health scare suffered by the duke, who is known for being a robust and active 90-year-old. In October, he joined the queen for an intensive 11-day tour of Australia.//DPA