Karl Mader studied for four years at the Graz School of Applied Arts, initially sculpture, then painting under A. Schrötter and in 1902/03 at the Vienna School of Applied Arts under A. Roller and at the Munich Academy under L. Herterich. He further trained with F. Hodler in Geneva and at the Académie Julian in Paris. He returned to Fürstenfeld in 1900, where he taught at the Staatsrealschule from 1909 to 1920. From 1920 to 1924 he taught at the Graz School of Arts and Crafts. After voluntarily giving up the teaching position, he lived as a freelance artist in Graz. From 1924 he was a member of the Association of Visual Artists of Styria and the Graz Artists' Association, and from 1935 a member of the Vienna Künstlerhaus.