Theodore Wells Pietsch was born in Chicago and educated in private schools. His professional formation included studies at the Massachusetts Institute of Technology from 1885 to 1889, employment in the office of Burnham & Root, and study at the Ecole des Beaux Arts in Paris from 1892 to 1898. Pietsch received a diploma from the French government in 1897 and honorable mention in the Salon of 1898.
Upon his return to the U.S., he went to work for Howard & Cauldwell in New York and then entered the office of the Supervising Architect of the U.S. Government. He was appointed chief designer in July 1902. He was elected to the Baltimore Chapter of the AIA in 1903; he opened an office in Baltimore in 1904. In Baltimore, he served as a judge for the Maryland Institute.
During World War II, he instructed officers in French at Camp Meade, 1917-18. A resident of Roland Park from 1920 to 1925, Pietsch died in 1930.