King Charles III has been crowned at London's Westminster Abbey in Britain's biggest ceremonial event for seven decades.
The Archbishop of Canterbury, Justin Welby, slowly placed the 360-year-old St Edward's Crown on top of the King's head.
Prince William, heir to the throne, pledged his allegiance to his father.
King Charles succeeded his mother Queen Elizabeth when she died last September and at 74, became the oldest British monarch to be crowned as he sat upon a 14th-century throne at Westminster Abbey.
Watched by about 100 heads of state and dignitaries, including US first lady Jill Biden, and millions on television, Charles followed his predecessors from the time of William the Conqueror in 1066 in being crowned at the abbey.
Charles looked serious as he swore oaths to govern justly and uphold the Church of England — of which he is the titular head.
He was then hidden from watching eyes by a screen for the most sacred part of the ceremony when he was anointed on his hands, head and breast by Archbishop of Canterbury Justin Welby with holy oil consecrated in Jerusalem.
After being presented with symbolic regalia, Welby placed the St Edward's Crown — which was made for Charles II in 1661 — on his head and the congregation cried out "God save the King".
His eldest son William, 40, then knelt before his father to pledge his loyalty as his "liege man of life and limb", both moments greeted by cheers from crowds outside.
Camilla, Charles's second wife, was crowned Queen during the 2-hour ceremony which, while rooted in history, attempted to present a forward-looking monarchy.
Tens of thousands of people ignored rain to line the streets of London to watch the royal procession.
"No other country could put on such a dazzling display — the processions, the pageantry, the ceremonies, and street parties," Prime Minister Rishi Sunak had said in the lead-up to the coronation.
Despite Mr Sunak's enthusiasm, the coronation is taking place amid a cost-of-living crisis and public scepticism, particularly among the young, about the role and relevance of the monarchy.
Earlier, Charles and Camilla made their way in the Diamond Jubilee State Coach as part of the procession from Buckingham Palace, down The Mall and Whitehall and on to the abbey.
Saturday's event was on a smaller scale than that staged for Queen Elizabeth in 1953, but still featured an array of historical regalia from golden orbs and bejewelled swords to a sceptre holding the world's largest colourless cut diamond.
Inside the abbey, bedecked with flowers and flags, politicians and representatives from Commonwealth nations took their seats alongside charity workers and celebrities, including actors Emma Thompson, Maggie Smith, Judi Dench and US singers Katy Perry and Lionel Richie.
Among them was Australian Prime Minster Anthony Albanese, who recently told the ABC that he believed Charles III would be a highly engaged King of Australia.
Much of the ceremony featured elements that Charles's forebears right back to King Edgar in 973 would recognise, officials said.
Handel's coronation anthem Zadok The Priest was sung as it has been at every coronation since 1727.
But there were new elements, including an anthem composed by Sir Andrew Lloyd Webber, famed for his West End and Broadway theatre shows, and a gospel choir.
Charles's grandson Prince George and the grandchildren of Camilla acted as pages, and although a Christian service, at the end there was an "unprecedented" greeting from faith leaders.
However, there was no formal role for Charles's younger son Prince Harry, after his high-profile falling out with his family.
Nor for his brother Prince Andrew, who was forced to quit royal duties because of his friendship with late US financier Jeffrey Epstein, a convicted sex offender.
They sat in the third row behind other working members of the royal family.
As he left the abbey, King Charles wore a silk and ermine robe and carried the Sovereign's Orb which dates back to 1661.
Charles and Camilla, 75, departed in the four-tonne Gold State Coach built for George III, the last king of Britain's American colonies, to ride to Buckingham Palace in a 1-mile procession of 4,000 military personnel from 39 nations.
'Not my King'
British police said they had arrested 52 people during its operation for the coronation of King Charles, detaining them for a range of offences including affray, breach of the peace and conspiracy to cause a public nuisance.
In a statement, the London police force said all those who had been held remained in custody.
Earlier, police had made a number of arrests, including that of anti-monarchy group Republic as part of what they called "a significant police operation" ahead of the coronation.
Republic said five of its supporters had been arrested and hundreds of its placards seized
London police chief Mark Rowley had warned on Friday that there would be a "very low tolerance for disruption".
There were more than 11,000 police officers on patrol in central London.
Some anti-monarchy protesters had held up signs saying "privatise them" and "abolish the monarchy, not the right to protest", and "Not My King".
Most of the anti-monarchy protesters on Saturday had congregated in Trafalgar Square next to the bronze statue of King Charles I, who was beheaded in 1649, leading to a short-lived republic.
A Reuters photographer said a number of protesters from the Just Stop Oil environmental group were also arrested.
Commissioner Rowley had said police would take action if protesters tried to "obstruct the enjoyment and celebration" of a significant number of people.
ABC/Reuters
