Bass Karl Huml was born and raised in Melbourne, Australia, where in 1995 he was the winner of the prestigious Sun Aria Award. Huml was also the winner of the German Opera Award and the Met Opera award that enabled him to compete in the semifinal auditions on the Metropolitan Opera stage in New York City. He studied singing in New York with Ruth Falcon.

Huml has been a member of the ensembles of Opera Australia, Oper Köln, Bremer Theater, and Volksoper Vienna.

Recent roles include Astradamors (Le Grand Macabre by Ligeti, Palermo), Roy Cohn (Angels in America by Péter Eötvös, Vienna), Pflege Jonas (Koma by Georg Friedrich Haas, Salzburger Festspiele), principal soloist (No. 50 [The Garden] by Richard Ayres, Asko | Schönberg Amsterdam), Doktor Raubenstock (world premieres of Die dunkle Seite des Mondes by Unsuk Chin, Hamburgische Staatsoper), and Fürst Isa (world premiere of Die Judith von Shimoda by Fabián Panisello, Bregenzer Festspiele). He also has a long association with Neue Oper Wien in Vienna.

Huml has appearedat the Salzburger Festspiele, Teatro San Carlo in Naples, Opera Australia, Hamburgische Staatsoper, Oper Köln, Maggio Musicale Fiorentino in Florence, Wiener Festwochen, Volksoper Wien, Teatro Massimo in Palermo, and Teatro Bellini in Catania.

He has collaborated with many celebrated stage directors, including Barrie Kosky, Elijah Moshinsky, Stefan Herheim, Dmitri Tcherniakov, Günter Krämer, Pier Luigi Pizzi, Marco Gandini, and Alessandro Talevi. Huml has worked with conductors Kent Nagano, Daniele Gatti, Simone Young, Gabriele Ferro, Omer Meir Wellber, Richard Hickox, Juras Valčuha, Stefan Soltész, and Gianluigi Gelmetti.