The King expressed his "profound sadness" as he paid tribute to King Harald V as his "dear cousin" on Friday.
The Norwegian monarch, Europe's oldest ruler, passed away at 6.35 am this morning at age 89, the Royal House announced.
In a personal message shared on the royal family's social media channels, Charles remembered the life of Harald, his second cousin, once removed, writing: "It is with the most profound sadness that my wife and I have learned of the death of my dear cousin, King Harald V of Norway.
"For thirty-five years, King Harald served his people with unwavering dedication, guiding Norway through times of great change with warmth and humility.
© Getty Images"As Norway mourns the loss of so towering a figure, my whole family join in remembering a much-loved kinsman and friend whose kindness, compassion and deep sense of duty echoed from across the sea and across the decades."
A special musical tribute will be played to King Harald at the Guard Change later on Friday, it's understood.
Charles added, signing the message with his personal signature and initial: "The United Kingdom and Norway share particularly close historical and family ties, with Britain one of the first countries to recognise Norwegian independence and establish diplomatic relations in 1905. These special bonds were even further strengthened during the dreadful trials of the Second World War and help to bind our two countries together.
"The Queen and I extend our deepest and most heartfelt condolences to Queen Sonja and all her family, as Britain shares in Norway’s grief at this time of such heartbreaking loss."
Following Harald's death, his son, Prince Haakon, has become King Haakon VIII, while Princess Mette-Marit will be Queen Consort. Their daughter, Princess Ingrid Alexandra, is now heir to the throne.
King Charles's unexpected link to King Harald of Norway
King Charles and King Harald may have ruled different kingdoms, but they shared a close bond and were second cousins once removed.
King Edward VII and Queen Alexandra of the United Kingdom – who had six children – were King Harald’s great-grandparents and King Charles’s great-great-grandparents.
© GettyTheir daughter, Maud, married Prince Carl of Denmark, who later took the name King Haakon VII when Norway gained independence in 1905. Their son, Olav, was the father of King Harald.
When King Charles was born in 1948, King Haakon VII served as one of his godparents. Known affectionately to his British family as "Uncle Charlie" (from his birth name, Carl), the former Norwegian monarch was rumoured to have inspired the naming of the future British King.
Charles's close bond with King Harald over the years
Harald attended the funeral of the late Queen Elizabeth II in 2022 alongside his wife Queen Sonja, and they were seen singing "God Save the King" in support of Charles.
King Harald also spent time with the late Queen, Charles, and Camilla during the D-Day 70 commemorations in 2014.
The Norwegian royals hosted Charles and Camilla – then Duke and Duchess of Cornwall – for a state visit in March 2012, as part of the late Queen's diamond jubilee celebrations.
© PoolThey waved goodbye to the British royals at the National Museum of Art and Architecture and were seen laughing and joking throughout the trip.
On the first day of the visit, all the stops were pulled out for a state dinner, also attended by Princess Astrid, Prince Haakon and his wife Crown Princess Mette-Marit, and Princess Martha Louise.
During a 2005 visit to the UK, Harald, Sonja and the Crown Prince couple were hosted by the late Queen, Prince Philip, and Charles and Camilla for a banquet at Buckingham Palace.
And in 1997, Charles travelled to Norway for Harald and Sonja's 60th birthday celebrations.
King Harald had experienced a period of ill-health for several years, including being hospitalised with haemolytic anaemia in August 2026. King Charles, meanwhile, continues to undergo treatment following his cancer diagnosis in 2024.
