Domagk earned a medical degree from the University of Kiel in 1921. After teaching at the universities of Greifswald (1924) and Munich (1925), he became director of the I.G. Farbenindustrie (Bayer) Laboratory for Experimental Pathology and Bacteriology, Wuppertal-Elberfeld. There, inspired by the ideas of Paul Ehrlich, he began testing newly developed dyes for their possible effects against various infections. He noticed the antibacterial action of one of the dyes against streptococcal infection in mice. The dye, Prontosil red, was then tried clinically against streptococcal infections in humans with great success. The active component of Prontosil turned out to be sulfanilamide, which became another important sulfa drug.

Unable to accept the Nobel award at the time because of Nazi German policy, Domagk later (1947) received the gold medal and diploma. He also was active in research on tuberculosis and cancer.