Watch Prince George, Princess Charlotte and Prince Louis Make Their Carriage Debut at Trooping the Colour

The siblings were accompanied by their mom, Kate Middleton, and Camilla, Duchess of Cornwall.

Queen Elizabeth's Platinum Jubilee kicked off in a big way on Thursday morning, with Prince George, Princess Charlotte, and Prince Louis making their carriage debut at the Trooping the Colour. The siblings were accompanied by their mom, Kate Middleton, and Camilla, Duchess of Cornwall.

George, 8, Charlotte, 7, and Louis, 4, wore color-coordinated blue outfits, with the boys in shirts and ties -- the eldest sibling even sported a suit jacket -- while their sister looked as sweet as ever in a baby doll dress. The Duchess of Cambridge, meanwhile, looked radiant in white dress by Alexander McQueen, and a white and blue Philip Treacy hat.

While all the kids looked adorable, it was Louis' outfit that caught the most attention as it was a recycled piece from his dad, Prince William's closet. Louis rocked the same mini sailor suit that the Duke of Cambridge wore to the same event as a toddler in 1985.

During their carriage debut, George, Charlotte, and Louis waved to the thousands of well-wishers they passed. At one point, Charlotte stopped to give herself a break, and made it a point to hilariously make sure her younger brother followed her lead. As George continued greeting onlookers with a smile, Charlotte stopped Louis from waving by taking his hand and placing it on his lap.

Ahead of the event, a new photo of Queen Elizabeth taken by Ranald Mackechnie at Windsor Castle in Maywas released along with a message from Her Majesty.

Karwai Tang/WireImage

“Thank you to everyone who has been involved in convening communities, families, neighbours and friends to mark my Platinum Jubilee, in the United Kingdom and across the Commonwealth," she shared.

“I know that many happy memories will be created at these festive occasions," the Queen added. "I continue to be inspired by the goodwill shown to me, and hope that the coming days will provide an opportunity to reflect on all that has been achieved during the last seventy years, as we look to the future with confidence and enthusiasm."

Ian Vogler/WPA Pool/Getty Images

The Platinum Jubilee festivities -- which celebrates Queen Elizabeth's 70-year rule over the United Kingdom and its 14 Commonwealth nations -- will continue throughout the weekend.

RELATED CONTENT: