The monarch appeared on the balcony of Buckingham Palace wearing a Stewart Parvin outfit – a vibrant green double crepe wool dress and coat, adorned with the Bow Brooch.
Her outfit was finished off with a Rachel Trevor-Morgan hat with a black pom-pom, pearl jewellery and white gloves.
The Duchess of Cornwall also wore green earlier on Sunday when she attended a Big Jubilee Lunch in south London.
For that event, Camilla wore an emerald green embroidered coat dress by Fiona Clare.
Later on at the pageant, Camilla wore a white coat with dark trim around the neckline and down the front.
The Duchess of Cambridge opted for pink at the pageant, wearing a long-sleeved pink dress with ruched front detailing.
Like the Queen and the Duchess of Cornwall, the Countess of Wessex also wore green on Sunday.
Sophie wore a green belted jacket over white trousers when she joined thousands of people at a picnic near Windsor Castle.