Charles, 77, enjoyed a dram of award-winning whisky and hosted a reception marking the Scotland Investment Forum.
Around 130 people from businesses were welcomed to the event at the Palace of Holyroodhouse in Edinburgh to celebrate Scottish entrepreneurialism.
The monarch was joined at the event by John Swinney, First Minister of Scotland, and Kate Forbes, Deputy First Minister.
The King, who is currently staying at Balmoral as a post-Christmas tradition, is not expected to meet with his youngest son, Harry, while he is in London for the trial against Associated Newspapers Ltd (ANL).
WATCH: King Charles tries whisky at reception in Scotland
Harry is part of a group of claimants with Sir Elton John and his husband David Furnish, campaigner Baroness Doreen Lawrence, politician Sir Simon Hughes, and actresses Sadie Frost and Liz Hurley, who all allege ANL had a practice of "clear systematic and sustained use of unlawful information gathering". The publisher vehemently denies the allegations.
Leonard Russell from Ian MacLeod Distillers enjoyed a dram of whisky with the monarch and ministers
During the reception, Charles enjoyed a sip from a £1,800 bottle of Lowland Single Malt Scotch Whisky from firm Rosebank, whose distillery is based in Falkirk.
Managing director Leonard Russell warned the King: "Be careful sir, it's high strength." Before taking a sip, Charles turned to John Swinney and quipped: "The terrible thing about it is, the photograph is never the most fetching." He later described the whisky as having a "toffee" flavour.
Speaking afterwards, Mr Leonard said: "He didn't look unhappy."
He added: "He said it had a nose of toffee, which is what you get from long-aged whisky. I think we are honoured that the King is bringing to attention businesses in Scotland, it's a remarkable thing."
Charles also met local business leaders and joined a reception for 130 representatives from Scottish firms and investors in the Throne Room.
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