The Queen led commemorations at the memorial to "The Glorious Dead" in Whitehall, while services were held at churches, war memorials and cemeteries across the country.
This was the 100th ceremony at the Cenotaph, following a tradition first begun after the first world war when thousands flooded into London and the memorial became a focal point for the bereaved.
The start and end of the short period of reflection for those killed in conflicts past and present was marked by the firing of a gun by the King's Troop Royal Horse Artillery, positioned on Horse Guards Parade.
The Duchess of Cambridge at the annual Remembrance Day Service at the Cenotaph in London.
He said: "We remember the many fearless people from Britain and all across the world who put their lives on the line making huge sacrifices in two world wars which cost the lives of millions, and in all other conflicts since".
Carrie Symonds (left), the partner of Prime Minister Boris Johnson, and Catherine Swindley, the wife of Commons Speaker Sir Lindsay Hoyle, during the Remembrance Sunday service at the Cenotaph memorial in Whitehall, central London.
Five former prime ministers - Sir John Major, Tony Blair, Gordon Brown, David Cameron and Theresa May - as well as Mayor of London Sadiq Khan, were also present to pay their respects.
Unsurprisingly, all eyes were on Prince William and Prince Harry, as this was their first royal engagement together since Harry's comments in a recent documentary confirmed they are "on different paths at the moment".
After the service, a large crowd cheered as veterans, and others involved in armed service personnel organisations and charities, performed the traditional march past.
Veterans in wheelchairs and walking sticks wore poppies to honor those who died during the wars. The march-past salute was taken by the Duke of York, who was accompanied by the Defence Secretary, Ben Wallace.