The Prince and Princess of Wales, Zara and Mike Tindall and the Duke and Duchess of Edinburgh were also among those in Kemble, Gloucestershire.
The King and Queen were greeted by cheers from well-wishers as they arrived at the wedding of the Princess Royal’s son Peter Phillips.
Charles and Camilla joined members of the royal family including the Prince and Princess of Wales, Zara and Mike Tindall and the Duke and Duchess of Edinburgh in Kemble, Gloucestershire.
Members of the public from as far afield as Ireland also travelled to the event and cheered loudly as William and Kate arrived at All Saints Church.
Metal barriers, forming two pens for the media and public, were erected around the church and road closures were in place.
There were shouts of “hip hip hooray” as bride Harriet Sperling, an NHS nurse, arrived along with her three bridesmaids – Mr Phillips’s children Savannah, 15, and Isla, 14, as well as Ms Sperling’s teenage daughter Georgina.
Also in attendance were Princesses Eugenie and Beatrice, accompanied by their husbands Jack Brooksbank and Edoardo Mapelli Mozzi.
The Duke and Duchess of Sussex were not in attendance.
The church, with its tall spire, sits in the heart of Kemble.
Mr Phillips lives nearby on his mother’s Gatcombe Park estate in Minchinhampton.
The 48-year-old, the son of Anne and her first husband Captain Mark Phillips, is the King’s nephew, William and Harry’s first cousin, and the brother of Zara.
Mr Phillips split from his first wife Autumn in 2020 after 12 years of marriage and shares custody of their two children.
The pair married in a grand royal wedding in St George’s Chapel, Windsor Castle, in 2008.
Mr Phillips’s engagement to Ms Sperling, who he began dating in 2024, was announced in August last year.
The couple were guests of Charles and Camilla at Royal Ascot in June and were invited to take part in the traditional carriage procession the royal family makes on to the famous Berkshire racecourse to signal the start of the day.
The wedding falls on the same day as the Epsom Derby, with the King and Queen set to dash from the ceremony to the racecourse, ready to watch the highlight of the racing season and present the trophy to the winner.
