His teachers were Fritz Busch, Lazzaro Uzielli in Cologne and Max von Pauer and Joseph Haas in Stuttgart.
After he had earned his reputation in the late 1920s as accompanist to the violinist Adolf Busch at concerts in Rome, Amsterdam, Berlin and New York, he travelled with Yehudi Menuhin for two years throughout Europe and America.
When Ferdinand Leitner became Kapellmeister of the Theater am Nollendorfplatz in Berlin in 1943, two of his singers, Karl Schmitt-Walter and Walther Ludwig, joined Giesen in Stuttgart, whom he accompanied in their recitals.
They continued the tradition of German lieder singing and were then replaced by the next generation Dietrich Fischer-Dieskau, Hermann Prey and Fritz Wunderlich.
After 1945 he specialized in the accompaniment of song recitals, among others with Ernst Haefliger, but especially in the collaboration with the tenor Fritz Wunderlich.