3/11 was reactivated on 20 August 1950 at Camp Pendleton and was assigned to the 1st Marine Division, FMF. The battalion deployed in September 1950 to Kobe, Japan and participated in the Korean War, operating from Inchon, Seoul, the Chosin Reservoir, the East, Central, and Western Fronts. Third Battalion participated in the defense of the Korean Demilitarized Zone from July 1953 to February 1955. The battalion was relocated to Camp Pendleton in February 1955.