The baritone Klaus Häger trained in Cologne and Freiburg under Prof. Franz Müller-Heuser and Prof. Ingeborg Most. These were followed by masterclasses with Dietrich Fischer-Dieskau, Sena Jurinac, Ernst Haefliger and others.

Häger won a number of prizes at national and international competitions and from 1990 performed opera with the Hamburg State Opera and the Berlin State Opera.

Guest appearances have taken him to the opera houses of e.g. Berlin (Deutsche Oper and Komische Oper) Munich, Dresden, Cologne, Bonn, Madrid, Milan and Tokyo. Klaus Häger performed at many festivals, including the Salzburg and Bayreuth Festivals. He regularly gives guest performances in the major music centres of Germany, Europe and Asia, as well as at Carnegie Hall in New York. His collaboration with conductors such as Daniel Barenboim, Christian Thielemann, Zubin Mehta, Riccardo Chailly, René Jacobs and Helmuth Rilling shaped his artistic career. In particular, the great works of Johann Sebastian Bach and the operas composed by Wolfgang Amadeus Mozart have been reoccurring foci of his artistic work.

Klaus Häger hands down his knowledge and skills to future generations at masterclasses in Germany and abroad, as well as to students in his role as professor at the Rostock University of Music and Drama. He has held a position as visiting professor at the Hanns Eisler School of Music Berlin since winter semester 2022/23.