The former Prince Charles will be formally proclaimed King at a historic Accession Council, which will be broadcast to the nation for the first time ever.
King Charles III officially became the monarch when his mother Queen Elizabeth II died on Friday September 8 in Balmoral, Scotland.
The Accession Council, which is attended by Privy Councillors, will take place on Saturday morning at St James's Palace.
The events at the Accession Council usually takes place behind closed doors, but for the first time in history it will be televised.
That means Brits will be able to watch and take part in this historic moment. Here is everything you need to know.
What time is the Accession Council?
The Accession Council will take place at St James's Palace at 10am on Saturday, September 10.
According to the Royal.uk website: "The Accession council will be followed by the Principal Proclamation, which will be read at 11am from the balcony overlooking Friary Court at St James's Palace.
"The Proclamation will be read by Garter King of Arms, accompanied by the Earl Marshal, other Officers of Arms and the Serjeants at Arms."
A second proclamation will be read at midday in London.
How to watch the Accession Council live
Usually, members of the public aren't able to see what goes on inside the Accession Council.
However, for the first time in history, the Accession Council will be televised, Clarence House has confirmed.
Brits will be able to watch it live on BBC One.
What happens at the Accession Council?
Although Charles formally became King on September 8, the whole Privy Council is usually commend to oversee a formal proclamation of the new monarch.
The Accession Council is divided into two parts.
In the first part, King Charles III will not be present. The Privy Council will "proclaim the Sovereign, and formally approve various consequential Orders, including the arrangements for the Proclamation".
For the second part, the King will make his Declaration and sign an oath to upload the "security of the Church in Scotland and approve Orders in council which facilitate continuity of government".
The Principal Proclamation will then be read out. This will be the first public reading of it.
At midday a second Proclamation will be read in the City of London, at the Royal Exchange.
The next day, Sunday September 11, further proclamation will be read in Scotland, Northern Ireland and Wales at 12pm.
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