The soldier from the elite 42 Commando was on a patrol with the Afghan army in the Khorgajat area of the Nahr-e Saraj district, the Ministry of Defence said.
"The Royal Marine was part of a foot patrol in support of the Afghan National Army, when they came under small arms fire," explained Task Force Helmand spokesman Major Rolf Kurth.
"He died as a result of a gunshot wound sustained in the ambush. Our thoughts and prayers are with his family and friends in their time of grief."
A Ministry of Defence spokesman said the soldier was shot at "close range".
"Despite the best efforts of the medics on the ground and extraction by helicopter, he was pronounced dead on arrival at Camp Bastion Role 3 Hospital," he added.
The next of kin have been informed.
His death brings to 382 the number of British troops killed since operations in Afghanistan began in October 2001. Of these, at least 338 were killed in combat.
Britain has around 9,500 troops in Afghanistan, making it the second-largest contributor to the NATO-led International Security Assistance Force.
They are mainly based in Helmand, battling Taliban insurgents and training up local security forces. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2011
