As a singer, Klaus Eibensteiner was and is a member of a wide variety of solo ensembles. As a tenor soloist, his focus is on sacred music from the Renaissance to the Classical period, and on stage he has sung primarily in singspiels and works of the 20th and 21st centuries. He has been a founding member, arranger and pianist of the Salzburg Comedian Harmonists since 2001. He founded and artistically directed the series "Contemporary Vocal Music at Mirabell Palace," where he performed his own works and commissioned compositions, as well as cantatas by Johann Sebastian Bach. Since 1989, he has taught accompaniment, voice, musical theater for actors (as an assistant) and literary drama for singers at the Mozarteum University.