Under plans from Operation London Bridge, the arrangements for the death of the monarch had been in place for a number of years.
Her coffin will be returned to Buckingham Palace and placed in the throne room.
Here is all you need to know:
What happens to the Queen after her death?
Elizabeth II has died at her royal residence in Balmoral, Scotland.
The Queen had spent the final months of her life at the castle.
Her body will be taken to lie in rest at the Palace of Holyroodhouse in Edinburgh.
Elizabeth II’s coffin will be carried up the Royal Mile to St Giles’ cathedral for a service of reception.
The body will then be transported back to Buckingham Palace.
She will be placed in the throne room and watched over by four Grenadier Guards, who will have their bearskin hats inclined.
The Queen will later be moved to Westminster Hall to lie in state for four full days, before her funeral takes place at Westminster Abbey.
When is the Queen’s funeral?
Queen Elizabeth II’s funeral will take place on Monday 19 September.
It will be a new bank holiday after King Charles III approved plans.
How will the Queen’s body be transported to London?
The Royal Family announced plans for the Queen’s funeral on 19 September.
She will be flown to an RAF base outside the city and then taken by road to Buckingham Palace.
The statement explained: “On the afternoon of Tuesday 13th September, The Queen’s Coffin will travel from Scotland by Royal Air Force aircraft from Edinburgh Airport, arriving at RAF Northolt later that evening.
“The Coffin will be accompanied on the journey by The Princess Royal.
“The Queen’s Coffin will then be conveyed to Buckingham Palace by road, to rest in the Bow Room.
“On the afternoon of Wednesday 14th September, the Coffin will be borne in Procession on a Gun Carriage of The King’s Troop Royal Horse Artillery from Buckingham Palace to the Palace of Westminster, where The Queen will Lie-in-State in Westminster Hall until the morning of the State Funeral.”
What plans are in place after the Queen’s death?
Although plans have been in place for decades in a process dubbed “Operation London Bridge”, a series of documents obtained by political news outlet Politico details the specifics of the protocols when the monarch dies.
The security plan is outlined in full, detailing everything from how news of the monarch’s death will be shared to the public to how quickly Prince Charles will ascend the throne.
It also includes details on what will happen during the 10 days following the Queen’s death, including where her coffin will go, how Prince Charles will spend his first few days as King and how the prime minister will publicly address the news.
The day that the Queen dies will be referred to as D-Day, with every day afterwards referred to as D-Day+1 and D-Day+2 and so on, going up to and including D-Day+10.
Her funeral will take place 10 days after her death at Westminster Abbey and she will be buried at the King George VI Memorial Chapel in Windsor.