The Duke of Edinburgh, who is 95, will no longer carry out public engagements from the autumn of this year, Buckingham Palace has announced.
The Palace said in a statement that it was the Duke's decision taken with the support of the Queen.
The statement read:
"His Royal Highness The Duke of Edinburgh has decided that he will no longer carry out public engagements from the autumn of this year.
"In taking this decision, the Duke has the full support of the Queen. Prince Philip will attend previously scheduled engagements between now and August, both individually and accompanying the Queen."
The husband of one of the most famous women in the world, he is defined by his relationship to Elizabeth II and gave up a promising naval career to support his wife in her royal role.
Prince Philip could have been First Sea Lord - the professional head of the Navy - had he not married Princess Elizabeth.
But his naval career came to an end in 1951 due to the failing health of his father in law George VI, and when his wife became Queen a year later his destiny was set.
His life at sea - following distinguished service during the Second World War - was put aside for royal duty, but he has always maintained close connections to the armed forces and their organisations.
For Philip's 90th birthday, the Queen - who is well aware of what he sacrificed - poignantly bestowed upon him the title of Lord High Admiral, titular head of the Royal Navy.
A qualified pilot, he gained his RAF wings in 1953, helicopter wings in 1956 and private pilot's licence in 1959.
In a recent public engagement with the British military, the Duke of Edinburgh visited troops of 1st Battalion Grenadier Guards at Lille Barracks in Aldershot.
Prince Philip has been colonel of the Grenadier Guards since 1975 - a regiment that is renowned around the world for its tunics and bearskins.
While Philip was a cadet in the Royal Navy, he caught the eye of a 13-year-old Princess Elizabeth, when she visited the Britannia Royal Naval College in Dartmouth with her parents, the King and Queen.
During the Second World War, he saw active service from the Indian Ocean to the Mediterranean, and by 1945 was in Tokyo Bay as the Japanese surrendered.
He was mentioned in despatches for his service on battleship HMS Valiant in 1941.
In 1947 the Duke and then Princess Elizabeth married at Westminster Abbey.
They initially enjoyed a simple married life during stays on the island of Malta, where the Duke was stationed with the Navy.
"The Duke of Edinburgh is Patron, President or a member of over 780 organisations, with which he will continue to be associated."