A day of pomp and pageantry culminated with the new King and Queen joined by their family on the balcony of Buckingham Palace to mark the coronation.
Charles and Camilla, wearing their crowns, shared the adulation of the crowd with the Prince and Princess of Wales and their children, Prince George, Princess Charlotte and Prince Louis, before reappearing on their own one more time.
The couple looked relaxed after their momentous day, watched around the globe by millions, as Charles followed his mother, Queen Elizabeth II, to the throne.
The ceremony at Westminster Abbey brought together around 100 heads of state, kings and queens from across the globe, celebrities, everyday heroes and family and friends of the couple.
Global popstars Lionel Richie and Katy Perry were part of the 2,300-strong congregation, as was French President Emmanuel Macron, actresses Dame Judi Dench and Oscar-winner Dame Emma Thompson, presenters Ant and Dec and King Willem-Alexander and Queen Maxima of the Netherlands.
Also in the congregation was Prince Harry who, after months of tension in the royal family sparked by his tell-all memoir, had travelled alone from the US to attend his father’s coronation leaving his wife, Meghan Markle, and their two children at home.
He sat two rows behind his brother with the Duke of York’s family and when the congregation was invited to pay homage to the new monarch, he joined other royals to proclaim: “God save King Charles. Long live King Charles. May the King live forever.”
Charles’ grandson Louis, who turned five a few weeks ago, lightened the mood as he yawned and fidgeted during the ceremony, while big brother George was a page of honour helping to hold the long train of the King’s robe.
The historic moment came at a few minutes past midday, when the Archbishop of Canterbury Justin Welby placed St Edward’s Crown on Charles’ head and he became the 40th reigning sovereign to be crowned at Westminster Abbey, the nation’s coronation church since 1066.
The King then knelt at the abbey’s high altar and received homage from his son and heir, the Prince of Wales.
Princess Charlotte and Prince Louis at the coronation ceremony of King Charles III and Queen Camilla
William’s interaction with his father, where he touched St Edward’s Crown then kissed the King on the right cheek, appeared a poignant moment for the head of state.
As William knelt before Charles, who held his son’s hand between his palms, the future monarch said: “I, William, Prince of Wales, pledge my loyalty to you and faith and truth I will bear unto you, as your liege man of life and limb. So help me God.”
Charles delivered a King’s Prayer, the first time a monarch has spoken words to God aloud during a coronation, and he prayed to be a “blessing” to people of “every faith and conviction”.
In his sermon the archbishop told the nation’s new monarch “we crown a King to serve”.
Mr Welby spoke of how “Jesus Christ was anointed not to be served, but to serve” – adding: “The weight of the task given you today, Your Majesties, is only bearable by the spirit of God.”
The event also saw the role of the Armed Forces brought to the fore as they staged the biggest ceremonial military operation since Queen Elizabeth’s 1953 coronation, culminating in a 4,000-strong procession of servicemen and women from across the globe, that wound its way through the heart of the capital.
The ceremony, which traces it roots back to the medieval period, saw the King dressed in a series of garments signifying a symbolic journey which concluded with him anointed with holy oil during its most sacred moment and crowned.
But in a change, the controversial “Homage of the People” element of the service was toned down after widespread criticism.
Instead Mr Welby “invited” a show of support from the congregation rather than a “call” to those in the abbey and elsewhere to swear allegiance to the King.
At the end of the day “unsuitable weather conditions” meant a planned flypast was curtailed to just the Red Arrows and a helicopter display which still enthralled the royals, who included the Princess Royal, Duke and Duchess of Edinburgh and their children and the King and Queen’s pages of honour.
Charles who wore the Imperial State Crown and Camilla, in Queen Mary’s Crown, were among the last to leave the balcony during an appearance which lasted almost 10 minutes and saw the crowd sing along when the national anthem was played.
But they were back a few minutes later by themselves and received a cheer from the crowds as they waved.
Away from the pageantry the Met Police were heavily criticised over the “incredibly alarming” arrests of Republican protesters ahead of the coronation.
It said 52 people had been arrested for affray, public order offences, breach of the peace and conspiracy to cause a public nuisance around the coronation.
Metropolitan Police Commander Karen Findlay acknowledged concerns about the arrest of protesters but defended Scotland Yard’s actions, saying: “Our duty is to do so in a proportionate manner in line with relevant legislation.”