Born in Schleiz, Germany, Bartholdt attended the public schools and Schleiz College (Gymnasium).
He immigrated to the United States in April 1872 and settled in Brooklyn, New New York He learned the printing trade and became a newspaper writer and publisher. He moved to Missouri and settled in Saint Louis in 1877.
He was connected with several papers as reporter, legislative correspondent, and editor, and at the time of his election to Congress was editor in chief of the Saint Louis Tribune.
Bartholdt was elected as a Republican to the Fifty-third and to the ten succeeding Congresses (March 4, 1893 – March 3, 1915). He served as chairman of the Committee on Immigration and Naturalization (Fifty-fourth Congress), Committee on Levees and Improvements of the Mississippi River (Fifty-fifth through Fifty-eighth Congresses), Committee on Public Buildings and Grounds (Fifty-ninth through Sixty-first Congresses).
In 1911 he was appointed by President Taft as a special envoy to the German Emperor to present a statue of Baron Steuben as a gift from Congress and the American people. He was not a candidate for renomination in 1914.
He served as chairman of the Republican State convention at Saint Joseph, Missouri, in 1896.
Bartholdt was elected president of the Interparliamentary Union at the conference held in Saint Louis in 1904, where in the following year he proposed "the most interesting recent suggestion for federating nations into a League of Peace". He was also for many years was president of the arbitration group in Congress, which he founded in 1903. Bartholdt was an Esperantist, and in 1914 he proposed a resolution to have Esperanto taught in American schools.
During World War I, he was president of the American Independence Union, which campaigned for an embargo on munitions sales by United States companies to belligerent countries.
He wrote an autobiography entitled From Steerage to Congress (Philadelphia: Dorrance, 1930). He died in Saint Louis, Missouri, on March 19, 1932.
His body was cremated and the ashes interred in Concordia Cemetery.
Member Saint Louis School Board, 1888-1892 (president, 1891-1892). Member 53d to 63d Congresses (1893-1915), 10th Missouri District.
Married Caecilie Niedner, June 27, 1880.