Corporal Walker was assigned to Company I, 3rd Battalion, 9th Infantry Regiment, 2nd Infantry Division. He was taken Prisoner of War while fighting the enemy in South Korea on 11 August 1950. He was presumed dead on 4 March 1954. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Walker was awarded the Purple Heart with Oak Leaf Cluster, the Combat Infantryman's Badge, the Prisoner of War Medal, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.