Patrol base 2 (PB2), in the Nahr-e Saraj district, has seen heavy fighting as insurgents tried to take control.
It is the last patrol base to close this year and the shutdown is one of the final roles for a number of Herrick 18 soldiers. Only four bases, plus Camp Bastion, will remain into next year.
Brigadier Rupert Jones, Commander Task Force Helmand, said: "The reality is the Afghans have not needed PB2, and that's very telling. The insurgents have not been able to re-infiltrate into say an area that used to be a hotbed."
The British presence will be almost halved by the end of 2013 to 5200. All combat operations should be over by the end of 2014.