Sam Johnson was born on October 11, 1930, in San Antonio, Texas, and he grew up in Dallas, Texas. He was commissioned through the Air Force ROTC Program on May 31, 1951, and he graduated from Undergraduate Pilot Training in August 1952. After completing combat crew training in the F-86 Sabre, Johnson was sent to Korea where he flew combat missions with the 16th Fighter Interceptor Squadron at Suwon AB, South Korea. During the Korean War, he was credited with shooting down one Mig-15 on May 23, 1953. He was also credited with one probable air victory and one damaged. After Korea, Johnson flew as an instructor pilot at Nellis AFB, Nevada, and was later selected to fly with the Thunderbirds Aerial Demonstration Team from March 1957 to October 1958. He flew with the 493rd Tactical Fighter Squadron at Chaumont AB, France, from January 1959 to January 1960, and with the same squadron but flying out of RAF Lakenheath, England, from January to April 1960. He served as the Chief of Weapons Training with the 48th Tactical Fighter Wing at Lakenheath from April 1960 to February 1962. He next served as Air Operations Officer and then Director of Operations and Training for the 4525th Student Squadron at Nellis AFB, Nevada, from February 1962 until February 1964. Johnson went through Counterinsurgency Indoctrination from February to July 1964, and then served with the 4520th Combat Crew Training Wing at Nellis AFB, from July 1964 to February 1966. During this time, Johnson served with Military Assistance Command Vietnam. He began flying combat missions in Southeast Asia in February 1966 with the 8th Tactical Fighter Wing, flying F-4 Phantoms out of Ubon AB, Thailand. On April 16, 1966, Major Johnson was forced to eject over North Vietnam and he was taken as a Prisoner of War. After spending 2,494 days in captivity, he was released during Operation Homecoming on February 12, 1973. After hospitalization, he went through National War College before serving as Deputy Commander for Operations and then Wing Inspector for the 4th Tactical Fighter Wing at Seymour Johnson AFB, North Carolina, from 1974 to 1976. His next assignment was as Commander of the 31st Tactical Fighter Wing at Homestead AFB, Florida, from 1976 until his retirement from the Air Force on April 30, 1979. After his retirement, Sam served in the Texas House of Representatives from 1985 to 1991, and he was elected as Representative of Texas' Third District in the United States Congress in 1991, serving until 2019. Sam Johnson Flew West on May 27, 2020, and was buried at Westland Memorial Park in Dallas, Texas. His wife, Shirley Lee Melton Johnson (1930-2015) is buried with him.

His 1st (of 2) Silver Star Citation reads:

Major Samuel R. Johnson distinguished himself by gallantry in connection with military operations against an opposing armed force in Southeast Asia on 16 April 1966. On that date, Major Johnson led a flight of two F-4C Fighter-Bombers on a twilight armed recce mission against a heavily defended target deep within hostile territory. Locating the target despite restricted visibility due to haze and terrain, Major Johnson encountered a curtain of flak as he rolled in for his first strike. Immediately altering his attack, although at a dangerously low altitude, he turned into the very teeth of fire from the menacing guns and continued to press the attack until his aircraft sustained mortal damage, forcing him to eject. This courageous act, attempted in the face of devastating ground fire at minimum altitude and great personal risk, epitomized the finest qualities of a true combat pilot. By his gallantry and devotion to duty, Major Johnson has reflected great credit upon himself and the United States Air Force.