In 1891 he earned his doctorate at the University of Bonn, where he was a student of Hermann Usener (1834–1905). Following graduation he remained in Bonn, where he assisted Usener with the works of Dionysius of Halicarnassus. In 1903 he became an associate professor at the University of Greifswald and three years later relocated to the University of Münster. In 1909 he succeeded Theodor Gomperz (1832-1912) as chair of classical philology at the University of Vienna, and where he remained until his retirement in 1937. In 1915 he became a member of the Austrian Academy of Sciences (AAS).
Radermacher specialized in research of classical rhetoric, folklore and mythology. Among his many written works was an edition of Quintilian's twelve-volume book on best practices in education of a young orator, "Institutio Oratoria". A few of his other significant writings are: