The King and Queen will officially welcome the South Korean president to the UK on Tuesday and host a glittering state banquet in his honor at Buckingham Palace.
Charles and Camilla are hosting Yoon Suk Yeol and his wife Kim Keon Hee for the first state visit since the king's coronation and the second of his reign.
The Prince and Princess of Wales will play a key role in welcoming the President and First Lady to their hotel on Tuesday morning.
William and Kate will travel with Mr Yun and Mrs Kim to the welcoming ceremony at the Horse Guards Parade in central London, where the King and Queen will be waiting.
A guard of honor, formed by F Company's Scots Guards, will give a royal salute amid traditional pomp and pageantry and the King and Mr Yoon will inspect the troops on the parade ground.
Charles, Camilla, William and Kate and their guests will then travel in a carriage procession down The Mall at the Palace, before a private lunch and a visit to view the Royal Collection exhibits in the Picture Gallery.
Later, Mr Yoon will lay a wreath at the Tomb of the Unknown Warrior at Westminster Abbey and address members of both Houses of Parliament in the Royal Gallery at the Palace of Westminster.
In the evening, 170 guests will gather for the banquet, usually a white tie and tiara, in the Palace's luxurious ballroom.
The King and Queen are expected to be accompanied by William, Kate and other members of the royal family, while Charles and Mr Yun will make speeches.
Foreign ministers are usually invited too, meaning newly appointed Lord Cameron of Chipping Norton is likely to return to the royal residence for dinner, recalling his time as prime minister.
Yun, 62, is a known karaoke fan and in April he belted out a verse of one of his favorite songs, American Pie, at a White House dinner at the request of President Joe Biden during a state visit to the US.
He received applause.
Critics of Mr. Yoon, a former attorney general, have accused him of cracking down on free speech during his 18-month presidency and cracking down on fact-finding news in the name of fighting “fake news.”
Ms Kim, a 51-year-old former head of an art event planning firm, has also courted controversy.
She publicly apologized on television in 2021 after admitting she exaggerated her professional credentials when applying for university jobs a decade ago.
Mr Yoon and Ms Kim made a quiet arrival at Stansted Airport on Monday.
Ahead of his trip, Mr. Yoon said the world is facing a “polycrisis” of multiple conflicts and threats to humanity.
He told the Daily Telegraph that the wars in Ukraine and Israel, and rising tensions with Russia, North Korea and the South China Sea, had forced him to seek “very close security cooperation” with the West.
It secured a landmark deal with the US earlier this year to address the North Korean nuclear threat.
Mr Yun previously warned other world leaders about possible cooperation between North Korea and Russia after North Korean leader Kim Jong Un's face-to-face meeting with Russian President Vladimir Putin.
The King and South Korean President met last year at the reception for heads of state and foreign dignitaries at the Palace on the eve of the late Queen's funeral.
Mr Yoon's opponents accused him of disrespect during his trip to London after he missed a chance to see the late queen's coffin in state – which he blamed on heavy traffic.
He was also caught on microphone swearing after a conversation with Biden at the UN general assembly the following week, with the video going viral in his country.
The King visited South Korea in November 1992.
As Prince of Wales, he toured with his then-wife, Diana, Princess of Wales, but the pair were dubbed ‘The Glums' because they looked cozy together, and a month later it was announced that Charles and Diana were divorcing. .
On Wednesday, Mr Youn will hold bilateral talks with Prime Minister Rishi Sunak in Downing Street and will also meet Labor leader Sir Keir Starmer.
The state visit follows the first incoming royal visit by South African President Cyril Ramaphosa last autumn.