In November 1898, Fordney defeated incumbent Democrat Ferdinand Brucker to be elected as a Republican from Michigan's 8th congressional district to the 56th United States Congress. He was subsequently re-elected to the eleven succeeding Congresses, serving from March 4, 1899 to March 3, 1923. Fordney served as the chairman of the Committee on Expenditures in the Department of the Navy in the 59th Congress; and of the Committee on Ways and Means in the 66th and 67th Congresses. He co-sponsored the 1922 Fordney–McCumber Tariff. He declined to be a candidate for renomination in 1922. He was also a delegate to the Republican National Conventions in 1908, 1924, and 1928.