The King will host his first state visit as monarch later as he welcomes the South African president to the UK.
King Charles and Camilla, the Queen Consort, will host a banquet for President Cyril Ramaphosa at Buckingham Palace as part of the two-day trip.
Ramaphosa is also set to address politicians in a joint sitting of both Houses of Parliament.
It is the first state visit to the UK in more than three years after they were stopped during the Covid pandemic.
The Prince and Princess of Wales will first greet the South African president at his London hotel on Tuesday morning and escort him to Horse Guards Parade for the ceremonial welcome with the King.
His Majesty will then ride down the Mall with Ramaphosa in a carriage procession to Buckingham Palace.
There the King will host the president at a private lunch and show him an exhibition of Royal Collection items relating to South Africa.
Ramaphosa, who has been head of government in South Africa since 2018, will follow the tradition of laying a wreath at the Tomb of the Unknown Warrior in Westminster Abbey, and then address MPs and peers in the Royal Gallery of the Palace of Westminster.
Later, the King will host a glittering white-tie banquet at Buckingham Palace for President Ramaphosa where both men will give speeches.
The visit follows the traditional format put in place during the reign of the late Queen Elizabeth II.