A procession of 10,000 people to the Cenotaph will give "a nation's thank you" to those who laid down their lives in World War One.
For the first time, members of the public chosen by ballot will pay their respects at the national memorial in Whitehall, central London.
It marks 100 years since Armistice Day, when WW1 officially ended on the 11th hour of the 11th day of the 11th month.
A series of a special events across the country are honouring those who died.
In France, where many of the battles of the Western Front were fought, 60 world leaders are gathering.
French President Emmanuel Macron will meet them for a ceremony at the Arc de Triomphe in Paris.
Sir Nicholas Soames, a Conservative MP and grandson of wartime leader Winston Churchill, branded him "inadequate".
The dukes and duchesses of Cambridge and Sussex, and Prime Minister Theresa May were among the audience at the annual Festival of Remembrance.
The royals stood as thousands of people in the audience held up photos of World War One soldiers - including Mrs May and husband Philip who held pictures of two of her ancestors.
Poppies fell from the ceiling of the iconic venue, after the Last Post was played.
A candlelit vigil was also held on the eve of Remembrance Sunday at the National Memorial Arboretum in Staffordshire.