Sergeant First Class Walker was a member of Battery B, 82nd Anti-Aircraft Artillery (Automatic Weapons) Battalion, 2nd Infantry Division. He was listed as Missing in Action while fighting the enemy in South Korea on 3 September 1950. He was presumed dead on 31 December 1953. 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, 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.