Karl-Heinz Lehner was born in Eggenburg in Austria. His first permanent engagement was at the Stadttheater Bremerhaven, after which he moved to the Dortmund Opera House. There, he acquired a large repertoire, before taking up a position at the Aalto-Musiktheater Essen. In 2000, he was awarded a prize for Best Young Artist by the State of Nordrhein-Westfalen for his portrayal of King Marke in Wagner's "Tristan und Isolde".
He made his Bayreuth debut in the 2016.17 season as Fafner in "Das Rheingold" and "Siegfried", Titurel in »Parsifal« and Nachtwächter in »Die Meistersinger von Nürnberg«. Guest engagements have taken him to the Hamburg State Opera, Bavarian State Opera, Semperoper Dresden, Opernhaus Graz, Komische Oper Berlin, Volksoper Wien, Oper Frankfurt, Aalto-Musiktheater Essen, Oper Leipzig, Semperoper Dresden, Teatro dell’Opera ub Rome and the Bregenz Festival. In addition to his busy opera schedule, Lehner is also a sought-after concert singer. He has sung at the Vienna Konzerthaus, Musikverein Vienna, Salzburg Festival, Konzerthaus Dortmund and the Philharmonie Essen. He has worked with conductors such as Georges Prêtre, Ulf Schirmer, Stefan Soltesz and Gabriel Feltz, as well as with directors such as Claus Guth, Jens-Daniel Herzog and Stefan Herheim.
In the 2019/20 season, he will take the stage as Baron Ochs in the new production of Richard Strauss' "Der Rosenkavalier".