The duchess did not attend Royal Ascot past year after she just gave birth to Prince Louis in April.
The duchess embraced the famed horse race's dress code in the powder-blue midi number, which featured lashings of lace, a dusting of embroidery across its sheer sleeves and pleated skirt, and a demure pussybow neckline. As the name suggests, this competition has a rich royal history, but it's only actually called Royal Ascot when the Queen attends - here's how Ascot's heritage ties in with the Royals and how it originated.
Thoroughbreds are the Queen's great passion, and she is probably never happier when working with John Warren, her bloodstock and racing adviser.
The design is believed to be a custom version of a dress from Saab's Resort 2019 collection, and appears to mark the first time the royal has worn a piece by the Damour-born couturier.
She is also a breeder of thoroughbreds with more than 20 Royal Ascot winners. Yes, we're talking about Royal Ascot, and no, the fashion did not disappoint. The Royal Enclosure is the most prestigious of Ascot's three enclosures and is where the Royals sit to watch the races.
Following in her aunt's footsteps, the young royal navigated her way across the grass in a pair of nude heels, while she brightened her look with a pale pink lip.
Punters like to bet on the colour of the Queen's hat and the monarch, who wore a duck egg blue outfit by Stewart Parvin and a matching Rachel Trevor-Morgan hat, picked the same hue as her appearance at Royal Ascot on Tuesday.
While Her Majesty usually attends the full five days, she's accompanied by various members of her family including her children, Prince Charles, Princess Anne, Prince Andrew and Edward.