She joined her husband Prince Harry and Queen Elizabeth II for the first day of the race meeting, which runs until June 23.
Harry and Meghan, who got married at Windsor Castle one month ago, are expected to present the winning trophy for the St James’s Palace Stakes, according to the Royal Ascot program.
The couple arrived in a horse-drawn carriage — a practice which began in 1825 with members of the royal family entering the course every day from Windsor Castle.
The Duchess of Sussex arrived dressed in a cream dress, with a cream and black hat; the Queen wore bright yellow.
Royal Ascot is Britain’s richest meeting — with a $9.7 million in prize pot and eight Group One races, the highest level in racing.
READ: Royal Ascot 2018: Security beefed up to avoid fighting among the finery
Meghan carried out her first official solo engagement alongside the Queen last week where they opened a new toll bridge in the northwest UK county of Cheshire.
Today, Kensington Palace also announced the couple will visit Dublin, Ireland next month on July 10 and 11.
“They are looking forward to learning more about Ireland’s history and experiencing its rich culture, as well as meeting the people who are shaping the country’s future,” the Palace tweeted.