The King was officially welcomed to Balmoral on Monday, as he takes up summer residence at the Castle.
In a small ceremony outside the Castle gates, Charles, 74, wearing a kilt, inspected a Guard of Honour formed of the Balaklava Company, 5th Battalion The Royal Regiment of Scotland, under the Command of Major Robert Weir.
The monarch was recently announced as Colonel-in-Chief of The Royal Regiment of Scotland, succeeding Her Late Majesty Queen Elizabeth II in the role.
Crowds of well-wishers stood outside the gates to catch a glimpse of the King as he was given a warm welcome to his Scottish residence.
The Pipes and Drums of 4 SCOTS performed at the ceremony, and The Royal Regiment of Scotland's Mascot, Shetland Pony Corporal Cruachan IV, was also present.
The 14-year-old pony famously took a bite out of the late Queen's posy during a visit to Stirling Castle in 2017, and tried to nibble Prince Harry's fingers during his visit to Edinburgh with wife-to-be Meghan Markle in 2018.
King Charles and Queen Camilla have been staying at Birkhall from the start of their summer break, with His Majesty also visiting the Castle of Mey.
MUST-SEE: 20 incredible photos of the royals enjoying their summer holiday at Balmoral
The couple are expected to welcome members of their families to Balmoral in the coming weeks, including the Prince and Princess of Wales and their three children.
Camilla also has two children from her first marriage to Andrew Parker Bowles – Tom Parker Bowles and Laura Lopes – as well as five grandchildren.
As per tradition, the King will also host Britain's Prime Minister Rishi Sunak and his wife Akshata Murthy for a weekend at Balmoral.
Charles and Camilla will reportedly still be residing in Scotland for the anniversary of the late Queen's death on 8 September, where they will spend the day privately.
No public event is planned, and Their Majesties will not hold a family gathering to mark the anniversary.
The King and Queen have attended a church service at nearby Crathie Kirk for the past two consecutive Sundays.
Following the Lionesses' heartbreaking defeat at the World Cup final against Spain in Australia, Charles sent a message of support, writing: “While I know how sore it must be, let none of you feel defeated, for to have reached the final at all is an immense tribute to your skill, determination and team spirit in the finest sporting tradition."