The King led the nation’s Remembrance Sunday commemorations as he laid a wreath at the Cenotaph during a two-minute silence.
Charles, who is still receiving cancer treatment, paid his respects without the Queen, who did not attend events in central London due to a chest infection.
He appeared alongside his son Prince William and daughter-in-law, Kate, Princess of Wales, who carried out two consecutive public engagements for the first time this year after her cancer treatment ended.
Sunday was the King’s third Remembrance service as monarch.
The Royal British Legion’s veteran parade along Whitehall featured 10,000 veterans from 326 different armed forces and civil organisations. Similar memorial events took place in Edinburgh, Cardiff, and Belfast, as well as smaller towns and cities.
Thousand of people, including Prime Minister Sir Keir Starmer and eight of his predecessors, watched as the nation fell silent at 11am.
Among the former leaders were Rishi Sunak, Liz Truss, Boris Johnson, Theresa May, Lord David Cameron, Gordon Brown, Sir Tony Blair, and Sir John Major.
On Saturday evening, the Prince and Princess of Wales attended the Festival of Remembrance at the Royal Albert Hall, along with the King.
Hours beforehand, Buckingham Palace announced Queen Camilla would not be attending either of the Remembrance events. It is understood there is no cause for concern but that doctors did not want to hinder her recovery or put anyone else at risk.
This year marks the 80th anniversary of the D-Day landings of the Second World War and the 25th anniversary of the end of the war in Kosovo.
It also marks the 75th anniversary of NATO and the 120th anniversary of the Entente Cordiale between the UK and France.