After arriving at Buckingham Palace by car, Kate and the children, Prince George, 11, Princess Charlotte and Prince Louis, 7, traveled in a traditional horse-drawn carriage down The Mall. Charlotte sat beside her mother, while her brothers faced backward across from them.

The only daughter of Prince William and Princess Kate coordinated with her mom in an aqua color for King Charles' birthday affair Trooping the Colour.

Kate Middleton is joining King Charles and Queen Camilla in a significant position at Trooping the Color. Why Princess Kate is with the King at Horse Guards Parade.

Kate Middleton and royal family unite at King Charles III's birthday parade, with the Princess of Wales wearing an ensemble reminiscent of late mother-in-law Princess Diana.

One of the most meaningful moments of Trooping the Colour happens at the finish when members of the royal family appear on the Buckingham Palace balcony to watch the RAF flypast, which every year, concludes the proceedings.

The parade travels from Buckingham Palace down The Mall to Horse Guards Parade. Then, following tradition, Charles, Queen Camilla, 77, and other work members of the royal family stoof on the Buckingham Palace balcony to watch a flypast. As the family headed back inside Buckingham Palace, Prince Louis turned and gave the crowd one final wave.

Ahead of Saturday's festivities, King Charles III also honored a handful of celebrities and public figures, including David Beckham, Gary Oldman and Elaine Paige.

Senior working royals including Prince William, Kate Middleton, Princess Anne, Prince Edward and Queen Camilla will reportedly take part in the king's birthday parade.