Joseph Tomanek was born in Prague. He left Czechoslovakia in 1910, emigrating to the United States where he began his working life as an interior designer. Tomanek attended art classes at the Art Institute of Chicago under a Antonin Sterba (1875-1963), who had been trained in the Paris academies, along with Albert Krehbiel and Karl Buehr..
Tomanek began painting modest nudes outdoors, bathed in sunshine at his outdoor studio in the Bohemian-American Hall in Chicago. Here he worked with his posing models on the roof, away from view of the windows of the neighbouring houses. Tomanek also painted several seascapes and landscapes, favouring the expanse of Lake Michigan, Indiana.
Tomanek became a member of the Bohemian Art Club in 1920 and also joined the Association of Chicago Painters and Sculptors, the Chicago Gallery Association and the Palette and Chisel Club. During the 1920s, thanks to three scholarships, Tomanek spent four years in Europe, a professional goal of many young American artists.
In 1938 Tomanek won the Logan Prize at the Art Institute of Chicago for Thoughts of the Future, a half-length nude strumming a guitar, which recalled the Salon days of Cabanel and Bouguereau for Peyton Boswell (Art Digest, 1 October 1938). He was one of the artists enrolled in the Illinois Art Project, 1935-1943. The Indianapolis Museum of Art has his painting Milking Time.