After graduation from law school, he began work in the insurance business. He was elected to the Minnesota House of Representatives in 1929 and served until 1935. In 1934, he had been an unsuccessful candidate for election to the 74th congress. After his six-year stint in the Minnesota House, Johnson served as Deputy Commissioner of Insurance and as the state Fire Marshal. A second Congressional run in 1936 was successful; Johnson served as a member of the Farmer-Labor Party in the 75th congress, (January 3, 1937–January 3, 1939). However, in 1938 he was defeated for re-election by Oscar Youngdahl, a Republican, and when he again ran in 1940 against Youngdahl he was again defeated.
Johnson resumed his insurance practice in Minneapolis and also operated a retail radio sales business. He died in Minneapolis in 1941.