The King will will return to the country on Friday as its monarch after serving for 64 years as the Prince of Wales.
Heading to Cardiff, the King and Queen Consort will first visit Llandaff Cathedral, then to the Senedd and lastly on to Cardiff Castle.
Members of the public have been invited to line the routes to all three locations, with people also allowed entry to Cardiff Castle on a first come, first served basis.
It will be the last destination on the tour of nations they embarked on after the King's proclamation as monarch, travelling more than 1,500 miles around the UK in his first week on the throne.
King Charles III and Queen Consort Camilla
UK PARLIAMENT/JESSICA TAYLOR
King Charles III and Camilla, Queen Consort mourning as Queen Elizabeth II is lying-in-state
POOL
As Charles sets foot on Welsh soil, after landing near the cathedral, a gun salute will be fired by the reservists from 104 Regiment Royal Artillery at Cardiff Castle.
Arriving at the cathedral by car he will be met by the Lord Lieutenant of South Glamorgan before taking part in a service of prayer and reflection for the life of the Queen, which will be led by the dean.
The Archbishop of Wales, Bishop of Bangor Andy John, will give an address, and First Minister Mark Drakeford is expected to give a reading.
Emerging from the cathedral they will greet mourners, well-wishers and schoolchildren before leaving to travel to the Senedd in Cardiff Bay.
Soldiers from 1st Battalion Welsh Guards, 1st The Queen’s Dragoon Guards, The Royal Welsh, sailors from the Royal Navy and RAF personnel will line the King’s path to the Senedd.
Trumpeters from The Regimental Band and Corps of Drums of The Royal Welsh will also perform.
The King will be presented with a motion of condolence in the Senedd’s main debating chamber by the leaders of the main parties.
Charles will then stand to reply and Llywydd Elin Jones MS, the Senedd’s presiding officer and speaker, will close the session.
The King may say a sentence in the country’s native language during his speech, as he has done in visits to the other devolved nations.
Charles and Camilla will then have a chance to read some of the condolence messages left by members during a special session on Sunday when the Senedd was recalled.
The new King and Queen Consort will go on a procession through the city on their way to Cardiff Castle.
At the castle, members of The Royal Welsh will be in place to receive the King, including Goat Major Sergeant Mark Jackson and Lance Corporal Shenkin IV, the regiment’s official mascot, a goat.
Farrier Major Mark Holland and Lance Corporal Emrys Forlan Jones, the regimental Welsh mountain pony from 1st The Queen’s Dragoon Guards, and 60 cadets from across Wales will also be present.
The King will have a private audience with Mr Drakeford and Senedd speaker Ms Jones.
In the castle’s Banqueting Hall Charles and Camilla will hold a reception for local charities and faith leaders.
Many roads in and around the city will be closed so walking or using public transport is advised, Cardiff Council said.
It comes after the King bestowed his former title of the Prince of Wales, Tywysog Cymru, on his son William on September 9, during his first speech as King a day after the Queen died.
William’s wife Kate, now the Princess of Wales, is the first to hold the title since Diana.