Johnson was elected as a Whig to the Thirty-first Congress (March 4, 1849 – March 3, 1851). He was nominated for reelection in 1850 but declined to accept. He resumed the practice of law in Owensboro and also engaged in agricultural pursuits. He was appointed judge of the Daviess County circuit court on May 4, 1867, and served until September 2 of that year. He died in Owensboro, Kentucky, on February 12, 1877. He was interred in Rosehill Elmwood Cemetery.