Yoon Suk-yeol and his wife Kim Keon-hee are in the UK for the first incoming state visit since the king’s coronation and the second of his reign.
The President and the first lady will be greeted at their hotel on Tuesday morning by the Prince and Princess of Wales.
Prince William and Princess Kate will travel with Mr Yoon and Ms Kim to the ceremonial welcome on Horse Guards Parade in central London, where the king and queen will be waiting.
A guard of honour, formed by F Company 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.
King Charles, Queen Camilla, Prince William and Princess Catherine and their guests will then travel in a carriage procession down The Mall to the palace, before a private lunch and a visit to see Royal Collection exhibits in the Picture Gallery.
Later, Mr Yoon will lay a wreath at the Grave of the Unknown Warrior in Westminster Abbey and deliver an address in the Royal Gallery at the Palace of Westminster to members of both Houses of Parliament.
In the evening, 170 guests will gather for the banquet, customarily a white tie and tiara affair, in the opulent palace ballroom.
The king and queen are expected to be joined by Prince William, Princess Catherine and other members of the royal family, while King Charles and Mr Yoon will make speeches.
King Charles III's first year – in pictures
Foreign secretaries are also usually invited, meaning the newly appointed Lord Cameron of Chipping Norton is likely to make a return to dining at the royal residence, harking back to the days when he was prime minister.
Mr Yoon, 62, is a known fan of karaoke and in April belted out a verse of one of his favourite songs, American Pie, at a White House dinner at the request of President Joe Biden during a state visit to the US.
He got a standing ovation.
Critics of Mr Yoon, a former prosecutor general, have accused him of suppressing freedom of speech during his 18-month presidency and cracking down on fault-finding news reports about him in the name of fighting “fake news”.
Ms Kim, a 51-year-old former head of an art event-planning company, has also attracted controversy.
She made a televised public apology in 2021 after admitting to exaggerating her professional credentials when applying for jobs at universities more than a decade ago.
Mr Yoon and Mrs Kim made a low-key arrival at Stansted Airport on Monday.
Before his trip, Mr Yoon said the world is facing a “polycrisis” of several conflicts and threats to humanity.
He told The Daily Telegraph that the wars in Ukraine and Israel, and rising tension with Russia, North Korea and in the South China Sea, have compelled him to seek “very close security co-operation” with the West.
He secured a landmark deal with the US earlier this year to counter the North Korean nuclear threat.
Mr Yoon previously warned fellow world leaders about possible co-operation 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 the South Korean President met last year at the reception for heads of state and official overseas guests at the palace on the eve of the late Queen Elizabeth’s funeral.
Mr Yoon’s opponents accused him of being disrespectful during his trip to London after he missed the chance to view the late queen’s coffin lying in state – which he blamed on heavy traffic.
He was also caught on microphone swearing after a chat with Mr Biden at the UN General Assembly the following week, with the footage going viral in his home country.
The king visited South Korea in November 1992.
As the Prince of Wales, he carried out the tour with his then-wife, Diana, Princess of Wales, but the pair were branded “The Glums” for looking ill at ease together and a month later it was announced they were separating.
On Wednesday, Mr Yoon will hold bilateral talks with Prime Minister Rishi Sunak at Downing Street and also meet Labour leader Sir Keir Starmer.
The state visit follows the first incoming one of the king’s reign by South Africa’s President Cyril Ramaphosa last autumn.
UK and South Korea to sign new partnership during presidential state visit
The UK and South Korea are set to sign a new long-term agreement covering defence and technology co-operation as President Yoon Suk Yeol arrives for a three-day state visit.
Mr Yoon begins his state visit on Tuesday, which will include a bilateral meeting with Prime Minister Rishi Sunak and the formal signing of the agreement in Downing Street on Wednesday.
Ahead of the visit, Mr Sunak pointed to the £21 billion ($26bn) which South Korean businesses commit in investment to the UK.
Trade and investment are expected to be the focus of the trip, with Trade Secretary Kemi Badenoch set to launch new negotiations on an upgraded free trade agreement.
The UK secured a free trade deal with South Korea in 2019, with the agreement largely aimed at keeping trade flowing post-Brexit and removing uncertainty.
“Long term, global partnerships are vital to our prosperity and security, both today and in the future. As two nations focused on innovation, harnessing new technologies and defending the international rules-based order, the UK and Republic of Korea are natural partners," Mr Sunak said.
“Through our new Downing Street Accord, we will drive investment, boost trade and build a friendship that not only supports global stability, but protects our interests and lasts the test of time.
“These close ties have already propelled £21 billion of investment between our countries.
“I know a free trade agreement fit for the future will only drive further investment, delivering on my promise to grow the economy and support highly-skilled jobs.”
The Downing Street Accord will see British and Korean militaries agree to step up joint training and operations, with the Asian state expected to agree to join with British ships on sanctions patrols.
It will, Downing Street said, also see the two countries work closer together on technology such as artificial intelligence, semi-conductors and quantum.
Science ministers will also sign a memorandum of understanding to boost space co-operation.
South Korea will host next year’s AI summit after the first UK-backed gathering in Bletchley Park earlier this month.
The trip to the UK coincides with the 140th anniversary of diplomatic relations between the UK and Korea, as well as the 70th anniversary of the armistice of the Korean war.