The King shared a warm embrace with his niece, Zara Tindall, as she and husband, former rugby star Mike, joined His Majesty at the opening day of Royal Ascot on Tuesday.
Charles, 74, was pictured kissing 42-year-old Zara after he and Queen Camilla arrived at the Berkshire racecourse in a carriage procession.
Equestrian Zara looked beautiful in a botanical print midi dress by Australian label, Leo Lin, and a bespoke boater-style hat by Sarah Cant, finishing off her look with a pair of embellished heels from Sauvereign.
The mum-of-three is said to share a close bond with her uncle Charles, and the pair have often been spotted hugging or sharing a giggle together at public events over the years.
It's no surprise given the tight-knit relationship between Charles and Zara's mother, the Princess Royal, who supported her brother in major roles at his coronation in May and Trooping the Colour this past week.
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The King and his niece also share a passion for horses and equestrian sports, with Zara winning a silver medal as part of Team GB's eventing team at the London 2012 Olympics.
Both Zara and her older brother, Peter Phillips, attended Charles and Camilla's nuptials in Windsor in 2005, with the future King and Queen returning the favour at Mike and Zara's Edinburgh wedding in 2011.
The Tindalls were also part of Charles's coronation celebrations, attending both the service at Westminster Abbey and the star-studded concert at Windsor Castle.
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Speaking about his dance moves at the bash on his podcast, The Good, The Bad & The Rugby, Mike said: "You can't hear Lionel Richie sing 'All Night Long' and not get up and dance.
"The worst thing was, with everything else, where you're going, 'Yeah I'll get up and dance to this,' and I was like 'Is the King not going to stand up?' because it takes a brave man to go out there [and do that]."
See Mike and Zara, and the Duchess of Edinburgh, dancing to Lionel Richie in the clip below...
Musing on his energetic dance moves, he added: "I broke my flag; I was that enthusiastic. I did think at one point, 'I really want to dance right now… rip my trousers off… we knew that Kermit was coming at some point, and I was like, 'Could I dance with Kermit the frog?'… I enjoyed myself."
He added: "It was phenomenal. It was an incredible weekend, and I thought the King was on point to a T and I think you could see how much he was concentrating and the emotion that was going into everything."
There was a huge royal turnout for the opening day of Royal Ascot, with the King and Queen joined by members of their family.
As well as Princess Anne and the Tindalls, Zara's older brother, Peter Phillips was in attendance with his girlfriend, Lindsay Steven.
The Duke and Duchess of Gloucester also arrived in the carriage procession, along with Camilla's sister, Annabel Elliot, and her son, Sir Ben Elliot and his wife, Mary-Clare.
The Queen's son, Tom Parker Bowles, was also spotted with his mother and stepfather in the royal box.
Meanwhile, Princess Beatrice made a stylish appearance in a Beulah London dress, attending with her husband and property developer, Edoardo Mapelli Mozzi.