It marked Kate's return to the event after missing it due to cancer treatment last year, and in a unprecedented move, she quickly repeated a stunning Self-Portrait outfit seen just a few weeks ago for the VE Day concert.
The Order of the Garter is the oldest and most senior Order of Chivalry in Britain, established by King Edward III nearly 700 years ago. The Order includes the King, who is sovereign of the Garter, the Queen, several members of the royal family, and up to 24 Companions.
Companions of the Garter are chosen personally by the sovereign to honour those who have held public office, who have contributed in a particular way to national life or who have served the Sovereign personally.
The ceremony took place two days after the royals came together to celebrate the King's official birthday at Trooping the Colour.
The Princess of Wales looked incredible in a white peplum-style outfit by Self-Portrait, which she sported for VE Day celebrations last month. She teamed the ensemble with a saucer-style hat by Sean Barrett with pearl jewellery.
Meanwhile, the Duchess of Edinburgh coordinated with Kate in a pale pink dress by Suzannah London with a wide-brimmed hat.
The senior royals walked in reverse precedence, so the Gloucesters at the front, followed by the Princess Royal, the Duke of Edinburgh and the Prince of Wales.
The Duke of Kent, 89, who is still a working royal, arrived at the service by car.
Meanwhile, the disgraced Duke of York has not taken part in the public procession since 2019.
However, he is believed to have joined the King and the rest of his family for the earlier investiture in the castle's Garter Throne Room and the traditional lunch that takes place afterwards in the Waterloo Chamber, both behind closed doors.
The formal royal naval officer did not walk in the procession as he has not been invested as a Royal Knight.
The last royal to have been given the honour was the Duchess of Gloucester in 2024.
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