He chatted enthusiastically with guests before the show, and attempted to put two youngsters, who were clearly nervous about meeting the King, at ease.
The monarch took the time to speak with Louie, 10, and Iris, eight, cracking jokes and displaying very warm body language.
Charles discussed his wife with Giles Cooper OBE, chairman of the Royal Variety Charity, and laughed his way through the show.
It was clear that he was happy to be there and was intent on carrying on as normal, even though his wife was unwell at home.
Hosts Alan Carr and Amanda Holden remarked how “amazingly charming” and “funny” he was on Friday night, and said they were in awe of honouring his commitment to attend while the Queen was unwell.
Comedian Matt Forde, whose impression of Donald Trump drew an amused reaction from the King, also said that the monarch appeared “very alert and full of life”.
Charles and Camilla are a close partnership, who will be celebrating their 20th wedding anniversary next April.
They’ve been through a lot together, having to navigate years of public vilification for their affair, which took years for many royalists to finally accept the relationship.
The Queen has been patient throughout, quietly supporting her husband and growing her patronages and royal work.
In turn, she’s won public affection and her dedication to duty has shone through, none more so than this year as she’s stepped up during the King and the Princess of Wales’s cancer battle.
They are an infamous duo and the King, while disappointed his wife could not join him on Friday night, will be grateful that her medics are taking every precaution to ensure she’s back to full fitness as quickly as possible.
He knows more than anyone that the royal doctors’ main priority is safeguarding their health, having been frustrated that he had to take a step back from his public-facing role when he commenced cancer treatment in February.