Two other unknown soldiers from Australia were also buried in the same ceremony on Tuesday.
They are believed to have been killed in the Battle of Passchendaele 101 years ago in Yypres, Belgium, between July and November 1917.
The ceremony took place at the Commonwealth War Graves Commission (CWGC) Tyne Cot Cemetery near where the bodies were discovered in 2016.
The moment the unidentified soldiers were buried
Ministers, dignitaries and current service personnel attended the ceremony.
Each year remains of around 40 British soldiers from the conflict are found on battlefields in Europe and the Ministry of Defence’s Joint Casualty and Compassionate Centre based at the cemetery tries to identify them.
The British soldier's regiment was identified as the Lancashire Fusiliers, which was disbanded after the war.
Researchers made the discovery thanks to the badges and buttons of the uniform that were found next to the remains - along with a pencil from Edgley Cricket Club.
They spent more than a year trying to identify the soldier, and will inscribe a name on the grave if DNA evidence can help solve the mystery in the future.
In order to identify the unknown soldiers, researchers ask potential relatives for DNA samples to test against those discovered.
Around 200 men from the Lancashire Fusiliers died during the battle, with only a few being identified.