The King has appeared in public for the first time since his cancer diagnosis was announced.
He was spotted with the Queen leaving Clarence House as they were taken by car to Buckingham Palace.
From there, they flew by helicopter to Sandringham where they arrived after 4.30pm on Tuesday afternoon.
Prince Harry had travelled on an overnight British Airways flight from Los Angeles airport, arriving at Heathrow at around 1pm on Tuesday.
He was photographed being driven into Clarence House, where the King had been recovering after receiving treatment.
Sky’s royal correspondent Laura Bundock said the meeting between the King and Harry was a “notable moment”.
“A royal reunion, but perhaps not a great reconciliation,” she said.
“Although, I think the fact that Prince Harry had to travel for thousands of miles for that 45 minute meeting – and bear in mind the two haven’t spoken in person for months – means it was significant.”
The King will continue working at Sandringham, with Bundock adding: “Those red boxes will be delivered here to this remote base of West Norfolk.
“But I think we are now facing a new reality, a moment of change, a moment of uncertainty, where the only certainty is the fact that things will be different and we won’t be seeing much of the King in the coming weeks.”
It is understood that Prince Harry has no plans to see Prince William during his visit to the UK.
The cancer was found after the King underwent treatment for an enlarged prostate – although Buckingham Palace said he does not have prostate cancer.
The monarch has begun a schedule of regular treatments and is said to be receiving expert medical care from a specialist team.
But he has been advised by doctors to postpone his public-facing duties.
Prince Harry’s visit comes after years of strained relations between him and his family, stemming from his departure from royal duties in early 2020 to live in the US with his wife Meghan and two children.
The couple cited the unbearable intrusions and racist attitudes of the British media as the reason for their departure.
The Duke of Sussex has since been critical of his family in TV interviews and in his book, Spare, which was published last year. The autobiography contained damning revelations about the prince’s relationships with his father and brother.