Prince William and Kate Middleton's titles as Prince and Princess of Wales are now official.

One day after Queen Elizabeth II's death in September 2022, King Charles III announced it on television.

The Letters Patent passed the Great Seal of the Realm on February 13, 2023, making the titles official.

Prince William and Kate were the Lord and Countess of Strathearn and Baron and Baroness of Carrickfergus.

Their Twitter and Instagram profiles were briefly renamed Duke and Duchess of Cornwall and Cambridge.

The Prince of Wales title is not automatic and must be bestowed by the monarch.

Letters patent are legal instruments used to express the monarch's will.

Prince William became Prince of Wales and Earl of Chester, making Kate the Countess of Chester.

Prince William won't have a Coronation ceremony like his father, but he may participate in King Charles' coronation on May 6.