Four generations of the Royal Family appeared on Buckingham Palace's balcony to watch the Red Arrows flypast, marking 80 years since the end of World War Two in Europe.
The King and senior royals watched on as a war-time Lancaster bomber led the 23-strong formation, including Typhoons and the Red Arrows, before waving to crowds below.
Following Queen Elizabeth II's death in 2022, this year is the first landmark Victory in Europe (VE Day) commemoration without any of the royals who stood on the balcony that day 80 years ago.
The King is overseeing the events, which span four days, and earlier included a military procession watched by the Prince and Princess of Wales and their children.
PA MediaAt noon, the ceremony began with a recitation of Sir Winston Churchill's famous VE Day speech by actor Timothy Spall.
The King and Queen were then joined by the Prince and Princess of Wales, and their children Prince George, Princess Charlotte and Prince Louis, to watch a military procession through the capital on Monday.
The military procession, including Nato allies and more than 1,300 members of the UK armed forces, made its way from Parliament Square to Buckingham Palace.
The King stood and saluted as the procession reached the Queen Victoria Memorial.
Later, the King and Queen were joined for the VE Day flypast on the Buckingham Palace balcony by Prince William and Catherine and their children, along with the Princess Royal, her husband Vice Adm Sir Tim Laurence, the Duke and Duchess of Edinburgh and the Duke of Kent - a first cousin of the late queen.
A Lancaster bomber - the most successful RAF heavy bomber of World War Two - led the VE Day flypast, accompanied by aircraft including fighters jets, transport aircraft and the Red Arrows.
The flyover narrowly avoided heavy rainfall as the weather began to change as crowds dispersed.
Getty ImagesAfter the display, Prince George joined his parents and the King at a veterans' tea party at Buckingham Palace, where he and Prince William spoke with 101-year-old Alfred Littlefield who served during D-Day.
Samantha Davidson, 57, from Deanmead, Hampshire, said: "The prince said George is very interested in finding out about the veterans.
"George even asked my grandfather how old he was during his service."
Veterans and senior politicians enjoyed a selection of finger sandwiches, soup and homemade scotch eggs.
The Royal Family is hoping "nothing will detract or distract" from the commemorations, following the Duke of Sussex's candid interview with the BBC on Friday, in which he discussed his estrangement from his father and desire for reconciliation.
A VE Day street party was hosted by the prime minister at Downing Street.
Sir Keir Starmer was joined by his wife Lady Starmer as they walked out of No 10 holding a plate of cakes, which he then handed out to some of the guests.
PA MediaVE Day was declared on 8 May 1945, after Britain and its allies formally accepted Nazi Germany's surrender after almost six years of war.
At 15:00, the then-Prime Minister Winston Churchill announced World War Two in Europe had come to an end.
Spontaneous celebrations erupted across the country, and the late queen and her sister Princess Margaret joined a group of friends to experience the excitement in London.
On Monday morning, the excitement began early for Maria and Chris Naynor and their three grandchildren, who left their home in Reading at 05:30 BST to get a prime spot along the Mall - armed with cream tea and gin and tonics.
Chris's father served in the armed forces and was wounded in Dunkirk, and his mother was out celebrating on the streets of London on VE Day in 1945.
Maria said it was critical to remember "all the people who gave their lives for freedom" and teach children about it.
PA MediaTo mark the historic event, the Cenotaph in Whitehall has been draped in a large Union flag - the first time the war memorial has been draped in Union Flags since it was unveiled by King George V more than a century ago, in 1920.
Watching from the Mall, Grace Gothard, from Mitcham, made her Union Flag dress draped with the Ghanian flag while Satvinder Cubb, from Chingford made a frock made from two "Lest we forget" scarves.
Satvinder said they wanted to be in the capital to remember all the people "who fought for us", as the last generation of World War Two veterans were growing older.
She described the message of VE Day as bringing together people from different countries and different age groups to say "why don't we unite together? Why can't there be peace?"
Street parties were held across the UK, with some councils such as Portsmouth waiving fees to close roads for the celebrations.
The Palace of Westminster, the Shard and Lowther Castle in Penrith are among buildings which will be illuminated from 21:00 BST on Tuesday.
A service at Westminster Abbey will begin with a national two-minute silence of remembrance on Thursday. Churches and cathedrals across the country will also ring their bells at 18:30 BST.
Pubs and bars in England and Wales which usually close at 23:00 BST will be able to keep serving for an extra two hours to celebrate on Thursday.
Additional reporting by Mallory Moench and Ashitha Nagesh
