The King wore a new tartan for his visit to the Braemar Royal Highland Gathering, a short distance from his summer residence at Balmoral in Aberdeenshire.
The King Charles III tartan, named after the monarch, is green, blue and red and was designed by the Scottish Tartans Authority earlier this year to mark the coronation.
The King was accompanied by the Queen, wearing an outfit by Mr Roy, with his sister the Princess Royal and her husband Vice Admiral Sir Tim Laurence.
Traditionally, the monarch becomes chief of the gathering, although Charles has not yet been announced as such.
The event is a favourite with the royals, and the family used a photograph taken at the games last year on one of their Christmas cards.