'Symbol of bravery'
Members of the royal family, senior government and General Richard Dannat, Britain's army chief, joined friends and family for Thursday's memorial service.
"Today marks the passing of a generation, and of a man who dedicated his final years to spreading the message of peace and reconciliation," Kevan Jones, Britain's veterans minister, said at the service.
"Active participation in the Great War is now no longer part of living memory in this country, but Harry Patch will continue to be a symbol of the bravery and sacrifice shown by him and those he served with."
Patch, who was nicknamed "The Last Tommy", only began talking about his experience of trench warfare when he turned 100, in an attempt to promote peace.
"War isn't worth one life," he had said, and described the battlefield as "mud, mud and more mud mixed together with blood".
"All over the battlefield the wounded were lying down, English and German all asking for help. We weren't like the Good Samaritan in the Bible, we were the robbers who passed and left them. You couldn't help them," he said.
The veteran also said he never killed anyone in combat, but had shot at the legs of a German soldier who had charged him with a bayonet.
Patch was wounded in a shell blast, which killed three members of his gun team.
An interview he gave in 2005 about his experiences inspired Radiohead, a British band, to write a song in his memory, which was released on Wednesday with the proceeds going to the Royal British Legion charity.
The veteran passed away on 25 July a week after Henry Allingham, who at the time was the oldest man in the world at 113.