The Princess of Wales and her family will not be at the service.
Charles, 75, will join the Queen and other members of the royal family at the annual Easter Mattins Service at St George’s Chapel at Windsor Castle on Sunday.
The Easter service comes just over a week after Kate released an emotional video message disclosing that she had started a course of preventative chemotherapy.
She, the Prince of Wales and their children Prince George, Princess Charlotte and Prince Louis, who all attended last year, will miss the service on Sunday.
The family are spending the Easter holidays together as they adjust to Kate’s diagnosis, which was discovered in post-operative tests after major abdominal surgery.
The King’s attendance at church will be seen as a move to reassure the public after the shock news about his daughter-in-law.
But the service will be a smaller version of the annual gathering, with fewer members of the royal family, as the King has paused public-facing duties while he continues treatment for cancer himself.
He was described by the Palace as being “so proud” of the princess for her courage in speaking out, and is said to be in “the closest contact with his beloved daughter-in-law”.
The King’s own treatment for cancer was announced at the start of February, but he has been carrying out low-key official duties behind palace walls.
Although the Easter service is within the grounds of the castle, the King and Queen will be seen arriving by the media.
Arrivals at the chapel’s Galilee Porch are often watched by staff living at Windsor, who usually gather on a grassy bank nearby or watch from their doorsteps.
Queen Elizabeth II is buried in the church’s tiny King George VI Memorial Chapel, with the Duke of Edinburgh and her parents George VI and the Queen Mother. Their names are inscribed on a new black stone slab set in the floor.