The serviceman, from the Argyll and Sutherland Highlanders, 5th Battalion, the Royal Regiment of Scotland, was killed on Saturday near to the Nahr-e Saraj district of Helmand Province.
He was part of an operation to halt the advance of enemy fighters at the time of the bomb blast.
The Ministry of Defence have confirmed his next of kin have been informed, but his identity has been revealed.
Lt Col David Eastman said: "The soldier was working in an area to the south of the Nahr-e Saraj district of Helmand Province, when he was caught in an explosion.
"He was part of an operation aiming to bring peace and prosperity to the people of a former insurgent haven, and has made the ultimate sacrifice in seeking a better life for others.
"He will remain in our thoughts and our deepest condolences go out to his family and friends."
A total of 349 UK military personnel have died since operations in Afghanistan began in 2001.