At the beginning of the Korean War, Poynter re-enlisted in the Marine Corps, joining the 13th Infantry Battalion, Marine Corps Reserve in Los Angeles on July 19, 1950. He was assigned to A Company, 1st Battalion, 7th Marine Regiment, 1st Marine Division, after the 7th Marines were activated on August 17 at Camp Pendleton. The 7th Marines and Poynter sailed for Japan on September 1. On September 21, the 7th Marines made an amphibious landing at Inchon, South Korea. His regiment including the 1st Battalion, then rejoined the 1st Marine Division which had made an assault landing at Inchon on September 15, and participated with the division in the battle of Seoul against North Korean forces; On September 24, Poynter took command of one of the rifle squads in A Company. On September 26, Poynter's rifle platoon led by their platoon commander, assaulted and overcame a well defended hill. The 7th Marines landed ashore next at Wonsan on October 27.