Looking exceptionally stunning in dresses by their own wedding designer's Kate and Meghan grinned from ear to ear when they saw Eugenie.
They are the daughters of Prince Andrew and Sarah Ferguson, who are divorced but enjoy an amicable relationship.
In attendance to witness the wedding of the ninth in line to the throne were 850 guests, including Queen Elizabeth II, Prince Philip, the Duke and Duchess of Cambridge, the Duke and Duchess of Sussex, Cara Delevingne, Kate Moss, Naomi Campbell and more-and the fashion was absolutely regal. No, no, Meghan and Harry aren't renewing their vows.
In another twist that bucked tradition, Princess Eugenie's dress also had a low, v-neck back, which showed off her large surgery scar with pride.
BBC News 24 broadcast footage of the princess walking into St George's Chapel inside Windsor Castle with her father Prince Andrew.
Eugenie and Brooksbank met while skiing in Switzerland in 2010.
Her Maid of Honor Princess Beatrice beamed as she looked on sweetly at her sister and best friend.
Une bague de champion du monde pour les Bleus — Equipe de France
Selon une information du Parisien publiée mardi , Paul Pogba va bientôt faire de ce rêve une réalité. De son côté, le sélectionneur Didier Deschamps a "trouvé ça très bien".
After the service, the couple took a horse-drawn carriage tour of Windsor before a reception at the castle hosted by the queen.
The strong winds forced many women to hold on to their elaborate hats as they approached the chapel.
The adorable bridesmaid, along with brother and page boy Prince George, has once again stolen the spotlight.
Eugenie kept her tiara on as well.
Singing and cheering well-wishers gathered outside in the streets of Windsor in the shadow of the castle, although there were far fewer people than crammed into the town for Harry's wedding.
He added on Instagram: "An incredible day, seeing two of the kindest and most lovely people in the world tie the knot".