Prince Philip conducted 219 royal engagements a year ago, and was in good form when he opened a new stand at Lord's Cricket Ground in London on Wednesday.
The palace released a statement: "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".
And it was business as usual once the fanfare died down, with a meeting of the members of the Order of Merit at St James's Palace proving his trademark wit had not deteriorated.
Prime Minister Theresa May has expressed "our deepest gratitude and good wishes" to Prince Philip following the announcement of his impending retirement, and has thanked him for supporting his wife, Queen Elizabeth II.
"I'm sorry to hear you're standing down", a noted mathematician reportedly said to the prince.
The queen's husband said Thursday he will carry out scheduled engagements for the next few months but won't take on new ones starting in the fall.
Both the queen and Philip have suffered some health issues in recent years.
But Buckingham Palace stressed he might decide to attend certain events from time to time.
"Although meetings involving the entire royal household are occasionally called, the way this has been done at the eleventh hour is highly unusual and suggests that there is something major to be disseminated", a source told the Daily Mail.
He is not expected to disappear completely from the public stage; the palace said he may still take part in some events from time to time.
Prime Minister Theresa May led the tributes to the Queen's consort, saying he has given the monarch "steadfast support", while Labour leader Jeremy Corbyn said the Duke's "clear sense of public duty" had inspired people for more than 60 years.
Prince Philip may have made a decision to step down from his public role as he approaches his 96th birthday, but he apparently has no intention to retire his famous one-liners.
One of the officials said the meeting is not related to the health of any senior royals. They married in 1947 and will celebrate their 70th wedding anniversary on Nov 20.
The announcement of the royal retirement followed an emergency meeting of her royal staff at Buckingham Palace earlier today. She has described him as "my strength and stay".
A member of the Greek royal family in exile, he gave up his naval career in 1952 when his wife was crowned Queen.