Kate Middleton and Prince William arrived in the royal carriage procession with Prince Charles and Camilla, the Duchess of Cornwall, while HRH - who also wore blue for the occasion - was joined in her carriage by Prince Andrew, the King of the Netherlands Willem-Alexander, and his wife, Queen Máxima.
Kate matched her blue dress with a Philip Treacy hat in the same colour, Kiki McDonough earrings and silver pumps. She wore her hair in a low bun and kept her makeup look minimal.
Another of our favourite royal looks was that of Zara Tindall, who paired a floral Zimmermann dress with a pale blue hat, similar to that of the Duchess of Sussex, and nude Gianvito Rossi heels.
Blue seemed to be the colour of the day with Queen Elizabeth and her granddaughters, Princess Eugenie and Princess Beatrice, matching Kate - and Zara's hat's - colour palette.
WATCH: The royals wear plumed hats for Garter Day service