After arriving at Dublin City Airport, Harry and Meghan were due to meet with Irish Prime Minister Leo Varadkar.
The Duchess also pushed boundaries by going bare-legged at the official photocall to announce her engagement to Prince Harry.
Their visit to Dublin will include Croke Park, Trinity College, and the starvation memorial, Irish Mirror reports.
It comes "at the request of Her Majesty's Government", a spokesperson for Kensington Palace said. Just hours after attending the Royal Air Force 100th Anniversary celebration this morning, the Duke and Duchess of Sussex hopped on a plane and arrived in Dublin, Ireland, to kick off their first royal engagement overseas post-wedding (before their royal tour of Oceania this fall).
Prince Louis' grandparents on both sides, Carole and Michael Middleton and the Duke and Duchess of Cornwall, all beamed with pride as they arrived at St James' Palace. The couple will attend a summer party at the British Ambassador's residence.
"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".
In 2011, the Queen became the first British monarch to visit Ireland since the visit by her grandfather, George V, in 1911.