Her majesty had summoned her most senior aides and the entire household to an emergency meeting at Buckingham Palace this morning to make the announcement.
In a statement, the Palace confirmed: "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. Thereafter, The Duke will not be accepting new invitations for visits and engagements, although he may still choose to attend certain public events from time to time.
"The Duke of Edinburgh is Patron, President or a member of over 780 organisations, with which he will continue to be associated, although he will no longer play an active role by attending engagements.
"Her Majesty will continue to carry out a full programme of official engagements with the support of members of the Royal Family."
The Lord Chamberlain, the most senior officer of the Royal Household, and Sir Christopher Geidt, Private Secretary, were thought to have addressed staff from royal residences as far afield as Balmoral.
Reports of the emergency meeting send social media into overdrive, speculating about the death of a senior royal or an abdication. However, palace insiders claimed neither scenario was likely, with sources warning there was "no cause for concern" or hysteria.
The Queen, who had been suffering ill health over Christmas, was seen on the gallops at Newmarket Wednesday morning with trainer William Haggas before hosting an audience with Prime Minister Theresa May at Buckingham Palace to confirm the dissolution of Parliament.
The Duke of Edinburgh, meanwhile, unveiled a new stand at Lord's Cricket Ground where he joked about being one of the most 'experienced unveiler of plaques in the world'.
Her Majesty turned 91 last month and Prince Philip will celebrate his 96th birthday in June.
In recent years the Queen has, slowly but surely, been handing over a number of her more onerous duties including long-haul travel to her heir, the Prince of Wales, and other senior royals.
Last year Buckingham Palace also announced that she would step down as patron of around 25 national organisations - including the NSPCC and Wimbledon tennis - after she turned 90 in April.
Many have expressed concern, however, that she still conducts well over 300 engagements every year.
Recently the Duke and Duchess of Cambridge announced they would be finally moving back to London from Norfolk, where Prince William works as an air ambulance pilot, in order to help shoulder the burden more.
The Duke of Edinburgh has also been curtailing his commitments, having stepped down from a number of patronages when he turned 90.
This story will be updated as we get more news.