King Charles Officially Names William and Kate Prince and Princess of Wales

Prince William and Kate Middleton are officially the Prince and Princess of Wales.

On Friday, King Charles III made the announcement as he addressed the United Kingdom for the first time since Queen Elizabeth II died at the age of 96. In his moving speech, he mourned the loss of his mother as he also assumed new responsibilities as monarch.

With the changing of the guard, Charles, 73, assumed the role of king. He announced on Friday that his wife, Camilla, will now be called Queen Consort and that Prince William, 40, and Kate Middleton, 40, will inherit the titles of Prince and Princess of Wales as of 6 p.m. local time Friday.

"As my Heir, William now assumes the Scottish titles which have meant so much to me.  He 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," King Charles added in the speech, recorded in Buckingham Palace's Blue Drawing Room.

"Today, I am proud to create him Prince of Wales, Tywysog Cymru, the country whose title I have been so greatly privileged to bear during so much of my life and duty," he added. "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 centre ground where vital help can be given."

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Chris Jackson/Getty Prince William; Kate Middleton

Following the Queen's death, William and Kate — who have been known as the Duke and Duchess of Cambridge since their April 2011 wedding day — updated their official @KensingtonRoyal Twitter and Instagram accounts as belonging to the "Duke and Duchess of Cornwall and Cambridge."

The Duke of Cornwall is traditionally held by the eldest son of the reigning British monarch, with his wife taking the Duchess title.

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As William and Kate take on their new titles, a royal source tells PEOPLE the couple is focused on "deepening the trust and respect of the people of Wales over time."

"The Prince and Princess of Wales will approach their roles in the modest and humble way they've approached their work previously," the source adds.

RELATED: Kate Middleton Is Set to Become Princess of Wales, Like Princess Diana Before Her

As Kate Middleton takes on the title of Princess of Wales, which William's mother, the late Princess Diana, once held, a royal source tells PEOPLE "the new Princess of Wales appreciates the history associated with this role but will understandably want to look to the future as she creates her own path."