The king and queen will remain in nearby Clarence House.
King Charles spoke about the importance of early cancer detection and cancer screenings in a video message on Friday.
Britain's King Charles III and Queen Camilla prayed Thursday with Pope Leo XIV in an historic visit to the Vatican to forge closer relations between the Church of England and the Catholic Church.
The meeting -- the first between the father and son in over one year -- took place as Harry was visiting the United Kingdom from his home in California for a series of engagements.
Harry challenged a U.K. government decision about his security.
The king's cancer diagnosis was announced publicly in February 2024.