Born and raised in Vienna, Clemens Unterreiner also spent his childhood in Graz and Budapest. He studied voice with Hilde Rössel-Majdan, Gottfried Hornik, Helena Lazarska and Wicus Slabbert.
In 2015 he will sing along with many other roles in the New Years Bat at the Vienna State Opera, Faninal at the easter-festival Baden-Baden and at the State Opera Tokyo, Brahm‘s Requiem at the Wiener Musikverein.
Since September 2005 Clemens Unterreiner has been a soloist and ensemble member at the Vienna State Opera where he could establish himself as one of the most popular young and upcoming baritones. He sings Sharpless, Faninal, Angelotti, Schtschelkalow, Schaunard, Donner, Melot, Harlekin and works together with conducters like Franz Welser-Möst,Christian Thielemann, Seiji Ozawa, Simon Rattle, Philippe Jordan, Leif Segerstam, MarcoArmiliato, Stefan Soltesz, Peter Schneider, Andris Nelsons, Fabio Luisi, Asher Fisch, YvesAbel, Dennis Russell Davies, Ádam Fischer and others. From the season 2008 he also sings as a guest solist Sharpless, Sprecher, Falke, Papageno at the Volksoper Wien.
He also performed at the Grand Hall of the Wiener Musikverein, at the Vienna Concert House (Wiener Konzerthaus), Palao de la Musica Barcelona and other international concert halls. He sang concert performances of "LaTraviata" - Germont, "Fidelio" - Pizarro and "Tosca" - Scarpia and in October 2002 he madehis opera debut at the State Theatre in Linz for the European première of "The Voyage" byPhilip Glass. During the summer of 2003 he sang Count Baccellone in "La Contessina".Further engagements took him 2004 at the Vienna State Opera where he performed in thepremière of Massenet’s "Werther". He sang Sharpless in "Madama Butterfly" in Chur,Straßburg and Großes Festspielhaus Salzburg which was awarded the Prize of the Music Theatre 2004 season.