The King was officially welcomed to Balmoral on Monday in brilliant August sunshine.
Charles, 76, has taken up his summer residence at his Scottish abode and is expected to host family members in the coming weeks.
The monarch, dressed smartly in a tweed jacket and a tartan kilt, inspected the Balaklava Company, 5th Battalion, The Royal Regiment of Scotland, at the gates of the royal residence.
As part of the guard of honour, the King also came face-to-face with an infamously cheeky Shetland pony, Cpl Cruachan IV, who is the mascot of the Royal Regiment of Scotland.
WATCH: Why Balmoral is so special to the royal family
The 16-year-old pony was famously told off by the late Queen Elizabeth II for nibbling on her flowers during a visit to Stirling Castle in 2017. But he was impeccably behaved as Charles stroked his nose.
Cpl Cruachan IV took up his role in October 2012 and met the late Queen on many occasions. He's proudly paraded at towns across Scotland, as well as royal residences, Balmoral, Buckingham Palace, St James's Palace and Windsor Castle.
Charles took his time to greet and chat with members of the public, who had stood outside the gates waiting for the King's arrival.
In the coming weeks, Charles is expected to host several of his family members at Balmoral, including the Princess Royal, the Prince and Princess of Wales and their children, the Duke and Duchess of Edinburgh, as well as his nieces and nephews.
The castle has been the private Highland home of the royal family since 1852.
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King Charles and Queen Camilla have attended a Sunday church service at Crathie Kirk near Balmoral Castle where they were joined by several high-profile guests
The Princess of Wales was seen formally greeting her stepmother-in-law as she and Prince William arrived in Windsor with Germany's President Frank-Walter Steinmeier
