He will hear condolences at Westminster before travelling to Edinburgh to mount a vigil for the Queen.
Image source, PA MediaKing Charles III is to speak to both Houses of Parliament for the first time as monarch.
Around 900 MPs and peers will meet the King at Westminster Hall to offer condolences on the death of Queen Elizabeth II.
The King will then travel to Edinburgh, where the Queen’s coffin is resting.
He will lead members of the Royal Family in a procession as her coffin travels from the Palace of Holyroodhouse to St Giles’ Cathedral.
At Westminster Hall, speakers from both Houses of Parliament, Sir Lindsay Hoyle and Lord McFall, will address the King.
The monarch, accompanied by Camilla, Queen Consort, will then give a reply.
After the King flies to Scotland, there will be a procession along the Royal Mile to St Giles’ Cathedral.
His Majesty will lead members of the Royal Family – expected to include the Queen’s other children the Princess Royal, Earl of Wessex and Duke of York – as they walk behind the Queen’s coffin.
At the cathedral they will be joined by a congregation drawn from all areas of Scottish society to attend a service of thanksgiving for her life.
Later in the evening, the King and his family will hold a vigil at the cathedral in honour of the Queen.
Her coffin will remain at the cathedral for 24 hours for members of the public to pay their respects, before being flown back to RAF Northolt and then travelling on to Buckingham Palace.
Before that, the King will return to the Palace of Holyroodhouse for an audience with Scotland’s First Minister Nicola Sturgeon.
He and the Queen Consort will then attend the Scottish Parliament, where members will deliver a motion of condolence at 17:30 BST.
Since the Queen died at Balmoral on Thursday, thousands of mourners have laid flowers and tributes at places she lived, including Buckingham Palace, Sandringham House and Windsor Castle.
More than 750,000 could file pass the Queen’s coffin in Westminster Hall during her lying-in-state later this week. Mourners wishing to do so been warned that queues could reach 20 hours.
The lying-in-state begins at 17:00 BST on Wednesday and will last until 06:30 on Monday 19 September – the day of the Queen’s funeral at Westminster Abbey.
