The Duchess, née Kate Middleton, will represent Her Majesty Queen Elizabeth II at celebrations to mark the 50th anniversary of Malta's independence on 20 and 21 September.
Clarence House confirmed the news on Monday following reports which have been swirling for several weeks.
The Duchess of Cambridge will visit Malta in September
Further details will be announced in due course.
The small Mediterranean island nation became a republic in 1974, but prior to this Queen Elizabeth II was their queen and head of state.
The Queen last visited Malta in 2007 and the British Monarchy twitter account tweeted on Monday: "The Queen and The Duke of Edinburgh lived in Malta when they were just married, while The Duke was on naval service."
The Queen and The Duke of Edinburgh lived in Malta when they were just married, while The Duke was on naval service. pic.twitter.com/gHNejjIaIj— BritishMonarchy (@BritishMonarchy) July 21, 2014
On Tuesday Kate will be celebrating the first birthday of her son, Prince George. In a brand new photo, released by Prince William and Kate, the little future King can be seen standing on his own two feet and walking unaided for the first time.
Royal fans can see just how much the little Prince has grown since his debut snap taken last August.
Judging by the new portrait of the royal darling, who is celebrating his first birthday next week, George has developed into a boisterous and charismatic little fellow – a sentiment echoed by dad William's recent comments that George is already "charging around and opening doors".
The Duchess of Cambrudge cheers on the tennis players during Wimbledon 2014
After watching Novak Djokovic win the Wimbledon Championship, Kate told the 27-year-old tennis player: "I'm slightly out of practice since having George," before adding that her and William "have quite a competitive game."