In typical style, the royal had expertly struck a balance between fashionable and formal, wearing a stunning white lace dress from Dolce & Gabbana.
Kate was lovely in lace
The dress might look familiar – it's the same one she wore to the Windsor Horse Race just last month. However, fans weren't able to get a good look at the designer number as Kate was wearing a red Zara jacket over the top.
This time, the 34-year-old let the dress take centre stage – much to fashion fans' delight! The beautiful white dress features sheer sleeves, a nipped-in waist and a tiered, swishy skirt. She topped off the look with a beautiful matching hat from Jane Taylor.
A Dolce & Gabbana hat topped off the look
The dress sold out within hours of the Duchess wearing it in May.
Kate was joined by Prince William as she turned up to the famous racing event.
The Dolce & Gabbana dress sold out within hours of Kate debuting it back in May
It has been a busy week for the Duchess, who was a prominent figure at the Queen's 90th birthday celebrations over the weekend – attending both Trooping the Colour and Sunday's Patron's Lunch on the Mall.
Kate first wore the dress back in May
Kate also stepped out in Windsor for the Order of the Garter ceremony on Monday, where she wowed in a scarlet Catherine Walker coat dress which she had previously worn on a royal tour of Canada in 2011.