Müller studied at the Academy of Fine Arts in Dresden and later continued his training in Munich. Deeply influenced by Impressionism, Jugendstil and Symbolism, he developed a lyrical style characteristic of German Expressionism. In 1910, he joined Die Brücke and, in 1912, also exhibited with artists of Der Blaue Reiter, maintaining close ties with Die Brücke even after its dissolution in 1913. After World War I, he became a professor at the Academy of Arts in Breslau. He primarily painted in distemper on coarse canvas, but also worked in lithography, woodcut and etching.