After an apprenticeship as a commercial artist, he became a soldier at the air raid defense during World War II, during which time he continued to draw and experiment with watercolor.
Following the war, Dahmen worked as a freelance painter after a brief stint at the Academy of Art in Dusseldorf. He became a co-founder of the 'Neue Aachener Gruppe' but like so many artists at the time, felt the pull to study the latest artistic trends in Paris, where he moved in 1951. For the following nine years Dahmen was involved and working with the famous Ecole de Paris movement.
He received his first international art award in Lausanne in 1959. Since the mid 60s, Damhen increasingly integrated different objects in his work. Between 1960-1967 he spent some time on Ibiza, where he received the graphic-prize in 1972.
In 1967 he assumed the post of Professor of Fine Arts at the Munich Academy.
Karl Fred Dahmen is equally esteemed for his paintings, constructions and his original graphic art.