From 1936 to 1940 Karl Stark was a student of sculpture in W. Gössner's class at the Graz School of Applied Arts. After an interruption due to four years of war service, he attended Rudolf Szyszkowitz's master class for painting for two years, and from 1947 to 1951 he studied at the Vienna Academy of Fine Arts. Early on in his career, Stark chose an expressive style of painting developed entirely from colour, thereby pursuing a path initiated by Richard Gerstl, Jean Egger or Herbert Boeckl. Distancing himself from the Viennese art scene, he and his family moved to Radlach in Carinthia. From 1956 to 1959 he was head of the graphics class at the Kunstgewerbeschule in Linz. In 1958 Stark moved back to Vienna, where he was represented by the Nebehay and Würthle galleries. Internationally, galleries such as Ror Valmar in Paris (1964) and the Galerie St. Etienne in New York (1967) dedicated exhibitions to him. In 1980, the artist founded Galerie Austria in Vienna, which specialised in the trade of Austrian classical modern art.