Hildegard Behrens was born in Varel (in the state of Niedersachsen-Friesland), Germany, on February 9, 1937. She was always known for an attractive, natural singing voice, but embarked on the study of law at the University of Freiburg, graduating as a junior barrister. Surprising her acquaintances, she decided to try for a musical career. She was accepted at the Freiburg Academy of Music, where she studied voice with Ines Leuwen. She became a member of the Opera Studio of the Deutsche Oper am Rhein in Düsseldorf in 1971. In 1972 she became part of (then) West Berlin's leading company, the Deutsche Oper, and appeared frequently in the leading houses of German-speaking Europe (Frankfurt Opera, Zürich Opera, Vienna State Opera, Salzburg Festival, and Bavarian State Opera), as well as the Paris Opéra. Her U.S. debut was at the Metropolitan Opera of New York, as Giorgetta in Puccini's Il Tabarro, October 15, 1976.
She had a strong dramatic soprano voice, clear and attractive; she sang the more powerful roles of the German repertoire and still maintained a warm vocal quality that brings an aspect of vulnerability to roles such as Brünnhilde in Wagner's Ring, Marie in Berg's Wozzeck, Janacek's Katya Kabanova, and Strauss's Salomé. She recorded most of these roles, and appeared in television productions of several operas as well. She also maintained a recital career.