Both the States of Guernsey and Alderney will hold special sittings at 11:00 BST to accept the proclamation.
On Guernsey, a public proclamation ceremony will take place at 12:00, following a march from St. James to the Crown Pier.
At the same moment, the islanders of Alderney will be invited to a proclamation at the Island Hall, where the Island Brass Band will play the national song.
On Saturday, in honour of the King's formal proclamation, flags across the Bailiwick were raised to full-mast.
The States of Guernsey have made the following statement: "The Channel Islands are the only section of the old Duchy of Normandy which remains loyal to the British Crown.
God Save the King (Dieu Sauve Le Roi) would be proclaimed on the island in honour of his accession to the throne, the document said in French.