In 1950, President of the United States Harry Truman nominated Johnson as Assistant Secretary of the Army (Research and Materiel).

He held this office until 1952, at which time President Truman nominated him as United States Under Secretary of the Army.

Upon leaving government service in 1954, Johnson became an executive at American Transport Association and Air Cargo Inc.

Upon retirement Johnson served on several boards and often provided strategic consulting services to several politicians and private corporations.

There were two services celebrating his life: 1) Christ Church, Greenwich, Connecticut, and 2) at Arlington National Cemetery, where there was a 21-gun salute in his honor.