Johnson was elected as a Democrat to the Thirty-third Congress (March 4, 1853 – March 3, 1855).
He was an unsuccessful candidate for reelection in 1854.
He moved to Minnesota in 1855 and settled in Winona.
He resumed the practice of law.
He served as president of the Winona & St. Peter Railroad during its construction to Rochester.
He moved to Owatonna, Minnesota, in 1865 and engaged in the practice of law.
He served as mayor and city justice 1867-1870.
Death
He died in Owatonna, Minnesota, February 4, 1896.
He was interred in Forest Hill Cemetery.