Kate Middleton dazzles in blue Elie Saab at the Royal Ascot

Beautiful in blue!

The Duchess of Cambridge joined Prince William, Prince Charles and the Duchess of Cornwall to kick off one of the biggest royal events of the year: the Royal Ascot! The annual five-day horse racing competition takes place every June, bringing together 300,000 guests near Windsor Castle dressed in their finest clothes, biggest hats and prettiest dresses.

The royal mom-of-three opted for a striking cornflower blue lace dress for the occasion, which she paired with a matching Philip Treacy hat embroidered with flower detailing. The custom Elie Saab dress is from the designer's Resort 2019 collection -- a short-sleeved version is available for purchase.

The duchess accessorized the look with a pair of matching earrings, an elegant updo and her engagement ring.

As noted by Harper's Bazaar, Kate's look on Tuesday is a major shakeup from past years. The duchess has only attended the event twice since marrying into the royal family, and both times opted for a simple white lace dress.

Joining in on today's festivities were other members of the royal family, including Princess Eugenie and Princess Beatrice, who both wore bright blue, Princess Anne and the Tindalls. The queen also arrived at the elegant soirée by carriage alongside Queen Maxima of the Netherlands, who likewise attended Monday's Order of the Garter.

While the Duchess of Sussex made her royal debut at last year's Ascot, she's expected to skip out on this year's event as she is still on maternity leave.

For more on the event, watch the video above!