Gibson graduated from Norwich University in 1923 and served on the faculty of New York Military Academy from 1923 to 1924. He was State's Attorney of Windham County from 1929 to 1933, assistant secretary of the Vermont State Senate from 1931 to 1933, and secretary of the Vermont State Senate from 1933 to 1940.

He was appointed to the U.S. Senate on June 24, 1940 as a Republican to fill the vacancy caused by the death of his father, Ernest W. Gibson. He served from June 24, 1940, to January 3, 1941, but did not run for election to fill the vacancy. He served in the South Pacific during World War II and was discharged as a colonel.

In 1946, Gibson challenged incumbent Governor Mortimer R. Proctor in the Republicans' gubernatorial primary. Gibson argued for change, saying "Under this rule a relatively small clique of people choose governors nearly 10 years in advance, supporting them up a series of political steps to the highest office." Gibson won the primary and was elected Governor in 1946, in what was called "a repudiation by Vermont voters of political practices and traditions that have been long established -- a rebellion, not against outright mismanagement and inefficiency in the state government at Montpelier, but rather against the inertia and lack of aggressiveness of administration policies." He resigned in 1950 to accept appointment as a United States district judge for the district of Vermont.