He worked as a millhand and lumberjack, became a farmer, and by 1913 was the leader of the Minnesota branch of the American Society of Equity and Vice President of the Equity-owned Equity Co-operative Grain Exchange and Farmers' Terminal Packing Co. He served in both the Minnesota House of Representatives and the Minnesota Senate before being elected to the U.S. Senate on the Farmer-Labor ticket, to fill the seat opened because of the death of Knute Nelson. Johnson served in the Senate from July 16, 1923, to March 3, 1925, in the 68th congress. He lost his bid for reelection in 1924. He was elected to the U.S. House of Representatives and served March 4, 1933, to January 3, 1935, in the 73rd congress, winning one of the general ticket seats. Subsequently, he resumed agricultural pursuits and served as state supervisor of public stockyards 1934–1936. He was an unsuccessful candidate for the Farmer-Labor nomination for Governor of Minnesota in 1936.[3]
Johnson died in Litchfield, where he had gone for medical treatment, on September 13, 1936, and his interment is in Dassel Community Cemetery in Dassel, Minnesota.
A son of his, Francis Austin Johnson (1904–1989) is the creator of the World's Biggest Ball of Twine; the twine ball rests under an enclosed pagoda in Darwin Township, Minnesota. He is interred in the same cemetery, near his father.