The King is to attend the annual Garter Day service at Windsor Castle next week, Buckingham Palace has announced.
Charles travelled to France for the D-Day 80th anniversary commemorations last week despite still undergoing treatment for cancer.
He will join the Queen and other members of the royal family at the traditional celebration next Monday.
His appearance will come just two days after a busy, high-profile appearance at Trooping the Colour on Saturday to mark the monarch’s official birthday.
Buckingham Palace said, after the snap General Election was called, that the royal family would postpone engagements “which may appear to divert attention or distract from the election campaign”, but it was not a blanket ban and visits would be considered on a case by case basis.
Garter Day sees Ladies and Knights of the Order of the Garter – the country’s oldest and most senior Order of Chivalry – process down the hill from the Berkshire castle’s State Apartments to St George’s Chapel, dressed in white plumed hats and dark blue velvet robes, watched by crowds of onlookers.
The Palace said Charles, Camilla and members of the royal family will depart by carriage afterwards and return to the castle.
The installation of new Companions of the Order – including composer Andrew Lloyd-Webber, who has been made a Knight Companion – will take place during the service.
Theatre impresario Lord Lloyd Webber, whose hit musicals include The Phantom Of The Opera, Cats, Jesus Christ Superstar and Joseph And The Amazing Technicolor Dreamcoat, will also attend a private investiture in the castle’s Garter Throne Room earlier in the day.
Also being invested will be the Duchess of Gloucester as a Royal Lady of the Garter, as well as Lord Kakkar, emeritus professor of surgery at University College London and Air Chief Marshal the Lord Peach, who have both been made Knight Companions.
Founded in 1348 by Edward III, the Garter is awarded by the sovereign for outstanding public service and achievement.