"The Queen died peacefully at Balmoral this afternoon," read a statement posted on the Buckingham Palace gates and the royal family website. "The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
Charles immediately became King following the death of his mother, who was 96 years old, and in an address this evening Prime Minister Liz Truss named the monarch as King Charles III.
As politicians and rulers across the globe pay tribute to the loss of Her Majesty, Putin sent a note to King Charles III to express his condolences.
"Your Majesty, please accept our deepest condolences on the passing of Queen Elizabeth II," he began.
Putin continued: "The most important events in the recent history of the United Kingdom are inextricably linked with the name of Her Majesty.
"For many decades, Elizabeth II rightfully enjoyed the love and respect of her subjects, as well as authority on the world stage.
"I wish you courage and perseverance in the face of this heavy, irreparable loss. I ask you to convey the words of sincere sympathy and support to the members of the royal family and all the people of Great Britain."
Putin's message came amid the ongoing war between Russia and Ukraine, which began in February when Putin sent troops across the border.
Prior to her death, Queen Elizabeth made reference to the ongoing war in a tribute to Ukraine and its people to mark the country's independence day last month.
She wrote: "It gives me great pleasure to send Your Excellency and the people of Ukraine my warmest greetings on the celebration of your Independence Day.
"In this most challenging year, I hope that today will be a time for the Ukrainian people, both in Ukraine and around the world, to celebrate their culture, history and identity. May we look to better times in the future."
The Ukrainian president, Volodymyr Zelenskyy, is among those who have paid tribute today as he wrote: "It is with deep sadness that we learned of the death of Her Majesty Queen Elizabeth II.
"On behalf of the people, we extend sincere condolences to the @RoyalFamily, the entire United Kingdom and the Commonwealth over this irreparable loss. Our thoughts and prayers are with you."Featured Image Credit: PA Images / Alamy ZUMA Press, Inc. / Alamy