“The Queen died peacefully at Balmoral this afternoon. The King and the Queen Consort will remain at Balmoral this evening and will return to London tomorrow,” Buckingham Palace announced.
Queen Elizabeth II was the longest-reigning monarch in British history and the world’s oldest head of state.
On her death, the Queen’s eldest son and heir, Charles, the former Prince of Wales, has become King of the United Kingdom and 14 Commonwealth realms.
No official details have been released about what will happen over the coming days, but it is anticipated that the Queen will be given a full state funeral, as is traditional to mark the death of a monarch.
It is also expected that her body will lie in state to allow the public to pay tribute.
The King will sign off the final plans in the coming days.
Princess Elizabeth became Queen in 1952 at the age of 25, when her father, King George VI, died.
Her coronation took place 16 months later at Westminster Abbey.
The Queen held a number of other titles, which will now automatically pass to her son and heir.
She was head of the Commonwealth, commander-in-chief of the British Armed Forces, and supreme governor of the Church of England. She was also patron of more than 600 charities and organisations.