The couple, who were given the title of Duke and Duchess of Cambridge on their wedding day in 2011, became the Duke and Duchess of Cambridge and Cornwall on Thursday.
On Friday, King Charles III, formerly Prince Charles, addressed the nation for the first time as monarch. During his speech, he also announced new titles for William, who is next in line to the throne, and Kate.
“As my heir, William now assumes the Scottish titles which have meant so much to me,” the king said, adding that his eldest son then “succeeds me as Duke of Cornwall and takes on the responsibilities for the Duchy of Cornwall which I have undertaken for more than five decades.”
Charles added that he was “proud to create” William as the new Prince of Wales, a “title I have been so greatly privileged to bear during so much of my life and duty.”
“With Catherine beside him, our new Prince and Princess of Wales will ― I know ― continue to inspire and lead our national conversations, helping to bring the marginal to the center ground where vital help can be given.”
The last person to use the Princess of Wales title was Princess Diana, who died in 1997. Though Camilla, now Queen Consort, also held the title, she did not use it.
Watch King Charles III’s first address to the United Kingdom and Commonwealth below: