Queen Elizabeth, Britain's longest-reigning monarch and the nation's figurehead for seven decades, died at her home in Scotland aged 96 on Thursday, Yeniavaz.com reports citing Buckingham Palace.
"The Queen died peacefully at Balmoral this afternoon," Buckingham Palace said in a statement. "The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
Elizabeth's eldest son Charles, 73, automatically becomes king of the United Kingdom and the head of state of 14 other realms including Australia, Canada and New Zealand. His wife Camilla becomes Queen Consort.
News that the queen's health was deteriorating emerged shortly after midday on Thursday when her doctors said she was under medical supervision, prompting her family to rush to be by her side at her Scottish home, Balmoral.
The queen had been suffering from what Buckingham Palace has called "episodic mobility problems" since the end of last year, forcing her to withdraw from nearly all her public engagements.
Her last public engagement came only on Tuesday, when she appointed Liz Truss prime minister - her 15th premier.
At her palaces and at government buildings across London, flags were lowered to half-mast.
Queen Elizabeth II, who was also the world's oldest and longest-serving head of state, came to the throne following the death of her father King George VI on Feb. 6, 1952, when she was just 25.