Joseph Fleck was born and raised in Austria and trained as an artist at the Academy of Fine Arts in Vienna. After serving on the Italian front in World War I, he emigrated to the United States in 1922, first landing in Kansas City. There, he saw an exhibit of the Taos Society of Artists, which prompted his move to Taos in 1924 or 1925.
Fleck lived and worked in Taos the majority of his life. While he followed and shared the artistic perspective and principles of the exclusive, conservative Taos Society of Artists (active from 1915 to 1927), painting Southwestern subjects—mostly portraits of Native peoples and Taos residents—in a realistic manner, Fleck was denied entry to the Society per its bylaws, which had been amended in 1919 during the Red Scare to restrict membership to American citizens (Fleck became a citizen in 1927). He was, however, a member of the Taos Artists Association.
During the New Deal, Fleck fulfilled commissions through the Public Works of Art Project and painted murals at post offices in Raton, NM, and Hugo, OK. After WWII, he turned his attention from portraiture to landscapes. His style evolved in step with his subjects, gradually loosening from an academic to a quasi-impressionistic approach. From 1942 to 1946, he served as the Dean of Fine Arts and artist-in-residence at the University of Missouri in Kansas City.