Around 4000 guests from the worlds of culture, art, heritage, film, TV, radio and fashion were invited to the prestigious event, from stars of stage and screen to those who work behind the scenes.
Among the well-known faces mingling on the palace lawn were Kate Moss, the model, Lenny Henry, the comedian, Tracey Emin, the artist, Sir Ridley Scott, the film-maker, and Arlene Phillips, former Strictly Come Dancing judge.
Other guests included Rosie Huntington-Whiteley and Toby Jones, the actor who played the lead role in Mr Bates vs the Post Office, the ITV drama about the Post Office scandal.
Louis Theroux, the documentary filmmaker, said he was “very flattered” to have been invited but joked that it “must have been a mistake”.
The 53-year-old said: “It’s illustrious company. It’s a beautiful day in a spectacular garden. I couldn’t tell if (the King) was a fan, but I would love to say he is.”
Sir Ridley, 86, who has directed Hollywood blockbusters including Gladiator and Alien, said he was “incredibly honoured” to have been invited.
Asked if the King was a fan of his films, he said: “No idea. But they have to watch something at night don’t they?”
Sir Ridley was made a Knight Grand Cross by the Prince of Wales during an investiture ceremony at Windsor Castle last week.
And earlier on Wednesday, he joined the King and Queen for a service of dedication for the Order of the British Empire at St Paul’s Cathedral, which he said was perfectly choreographed “just like a movie”.
The King was joined by the Queen, the Duke of Edinburgh and the Duchess of Gloucester at the event, held in glorious spring sunshine.
As is tradition at palace garden parties, the royals stood at the top of the garden steps to observe the national anthem before the crowd applauded.
The King and Queen then greeted groups of attendees separately.
The King wore his favoured grey morning suit with a pink waistcoat to match his wife’s pink fringed coat dress by Anna Valentine. The Queen also wore a pink diamond flower brooch that belonged to Elizabeth II.
Ms Emin, who was diagnosed with cancer in June 2020, said of her conversation with the monarch: “We spoke about health and painting. He asked me if I was recovering - which I am - and it was lovely to see the Queen too.
“I complimented them on their pinks - she said it was unintentional!”
Ms Phillips was also introduced to the Queen, who is a big Strictly fan.
She said: “She remembered me from when we last met. It was at a concert after I’d just been let go from Strictly and she said how much she missed me which was very kind.
“She asked me what I’ve been doing lately and I explained I was doing the choreography for Guys and Dolls. She said she had taken the grandchildren to see it and they loved it.”
The King was also introduced to married television presenters Vernon Kay and Tess Daly, “It was an honour to meet him,” Daly said. “He said he liked my dress.”
The King has been receiving treatment for an undisclosed form of cancer since early February but has recently returned to public duties.