Kate looked elegant in a blue Elie Saab dress and Philip Treacy hat as she accompanied her husband, Prince William, to the event which is attended by the royal family and the Queen each year.
While the rumours of another baby remain just that at the moment, Kate has been open about the struggles of being a parent in the past.
“It’s so hard. You get a lot of support with the baby as a mother, particularly in the early days, but after the age of one it falls away,” she told volunteers at the launch of the Family Action charity’s FamilyLine service in London in January.
“After that there isn’t a huge amount — lots of books to read. Everybody experiences the same struggle.”
While Royal Ascot was attended by many of the royal family, Meghan Markle, who made her Royal Ascot debut last year, wasn't in attendance at this year's event.
The Duchess of Sussex is still on maternity leave after the birth of her son, Archie, on May 6.