Harry, the Duke of Sussex, last saw his father in February last year shortly after it was announced that Charles was undergoing treatment for an unspecified form of cancer.
The prince's car was seen arriving at Charles' Clarence House home in London.
Charles, 76, held a royal audience there earlier in the day.
Neither Buckingham Palace nor Harry's spokesperson responded to a request for comment.
Harry, 40, flew into the United Kingdom on Monday for a series of engagements, and earlier on Wednesday visited a research centre which specialises in improving treatment for victims with blast injuries.
Since Harry and his US wife Meghan moved to California in 2020 where they now live with their two children, they have been highly critical of the royal family and the institution in interviews, TV documentaries and Harry's autobiography Spare.
Harry had some particularly barbed comments for Charles and his elder brother, heir-to-the-throne Prince William, leading to a total breakdown in his relationship with his family.
But after losing a legal battle with the the UK government over his security in May, Harry said he wanted a rapprochement.
"Of course some members of my family will never forgive me for writing a book. Of course they will never forgive me for lots of things. But you know ... I would love reconciliation with my family ... There's no point in continuing to fight anymore. And life is precious," he told the BBC.
"I don't know how much longer my father has. He won't speak to me because of this security stuff but it would be nice to reconcile."
Both Buckingham Palace and Harry's representatives had been tight-lipped about whether there would be a meeting ahead of Harry's visit to the UK.
However, the King's communications chief and Harry's media representatives were pictured in July at a secret meeting in London in what newspapers suggested might be the first steps towards a reconciliation.
