An average of nearly 12 million people in the UK watched the Platinum Party in the Palace on BBC One on Saturday.
The concert saw stars including Diana Ross, George Ezra, Queen and Elbow perform in front of a Buckingham Palace crowd including the Royal Family.
It attracted the BBC's biggest audience of the year, peaking at 13.4 million.
A huge pageant in central London and thousands of street parties across the UK are highlights of the final day of Jubilee celebrations.
Saturday evening's concert also saw speeches from Prince Charles and Prince William, with Charles paying tribute to the Queen and her reign of seven decades on the throne.
Its audience beats many other recent high-profile events - December's Strictly Come Dancing final averaged 11 million viewers; last month's Eurovision Song Contest averaged nearly nine million; and the Queen's Christmas message drew an audience of 8.96 million.
The BBC said it had a 74.3% share of the audience, adding: "The Platinum Party at the Palace on BBC One was the most watched programme of the year so far."
The Queen, who has been experiencing mobility problems in recent months, was not able to attend the event herself.
It began with a pre-filmed comedy sketch showing her sharing a pot of tea with Paddington Bear, where they both confessed to carrying around a marmalade sandwich.
Some 10 million people are expected to take part in the final day of Platinum Jubilee street parties and celebrations across the UK.
More than 85,000 have signed up to host Big Jubilee Lunches. Prince Charles and Camilla appeared at one at south London's Oval cricket ground on Sunday morning.
Meanwhile, the Duke and Duchess of Cambridge have tweeted pictures of Kate and their three children baking cakes in a kitchen decorated with Union Jack bunting.
Baking cakes for the local community in Cardiff to enjoy at a Platinum Jubilee street party taking place today! 🎉— The Duke and Duchess of Cambridge (@KensingtonRoyal) June 5, 2022
We hope you like them! 🧁 pic.twitter.com/lK9QkaGugB
The caption explained the cakes were for people in Cardiff to enjoy at a Platinum Jubilee street party taking place this weekend.
The Jubilee pageant, against the backdrop of Buckingham Palace, will involve more than 10,000 people, including key workers and members of the armed forces, as well as performers.
A two-mile carnival procession - featuring a huge cast, puppets and celebrities - will move down London's Mall and past the palace.
The evening finale at 17:00 BST will feature Ed Sheeran performing, and the singing of the national anthem in front of the palace.
Singer Elaine Paige, ambassador for the Royal Voluntary Service which hosted Platinum Champions at The Oval lunch, met Charles and Camilla at the event and said they seemed to be having a "marvellous time".
"I think he seemed very relaxed and full of good humour," she said. "I think his opening comment was - because it was only half past 11 - 'It's a little early for lunch'."
The West End star added the Queen's sketch with Paddington Bear showed perfect timing and said: "I thought to myself what a brilliant actor she is."
Sarah Friar, CEO of neighbourhood social media app Nextdoor, sat opposite the Prince of Wales. "He said at the end how great it was that everyone comes together this weekend," she said.
Ms Friar said Charles commented: "When it comes to Monday are we going to go back to all the bickering again? Let's hope we don't do that."
The Duke and Duchess of Cornwall are not the only royals to be at a Big Jubilee Lunch - Princess Beatrice and Princess Eugenie have been at an event organised by Westminster Council for local volunteer and community groups who helped during the Covid-19 pandemic.
The Cambridges were in Cardiff on Saturday as part of a series of visits to the UK nations by royals across the bank holiday weekend, which also saw Prince Edward and his wife Sophie meet crowds in Northern Ireland.
Princess Anne visited Edinburgh and represented the Queen at Saturday's Derby Day at Epsom.
Sunday's weather in much of the UK does not look ideal for outdoor festivities. England and Wales are forecast to see spells of heavy and thundery rain in places, with yellow weather warnings in place.
In London, where the pageant takes place, some sunshine is expected during the afternoon but heavy showers are likely too.
Northern Ireland and Scotland should be mostly sunny and dry, however.
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