King Charles III, her eldest son, has been heir apparent to the throne since 1952.
Aged 73, he will be the oldest person to ever become the monarch of the UK, surpassing 64-year-old William IV in 1830.
The Queen’s life in pictures
The new monarch said the royal family was in “profound mourning”.
“The death of my beloved Mother, Her Majesty The Queen, is a moment of the greatest sadness for me and all members of my family,” he said in a statement this morning.
“We mourn profoundly the passing of a cherished Sovereign and a much-loved Mother.
“I know her loss will be deeply felt throughout the country, the Realms and the Commonwealth, and by countless people around the world.
“During this period of mourning and change, my family and I will be comforted and sustained by our knowledge of the respect and deep affection in which The Queen was so widely held.”
Clarence House confirmed early this morning that Charles would take the throne as King Charles III.
His wife Camilla will be known as Queen Consort.
Prince William, Charles’ eldest son and the new heir to the throne, will inherit his father’s title as Duke of Cornwall – but the title of Prince of Wales will have to be officially re-bestowed.
Charles has in recent years become active in environmental issues, speaking on the need for green living.
However, he has also acknowledged that he understands the role of a constitutional monarch is different to that of a prince, seeming to indicate he will step back from pushing his favoured causes as king.
He will be the first British monarch to go by Charles since the death of Charles II in 1685.
