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 and upcoming baritones. He sings Sharpless, Faninal, Angelotti, Schtschelkalow, Schaunard, Donner, Melot, Harlekin and works together with conducters like Franz Welser-Möst, Christian Thielemann, Simon Rattle, Philippe Jordan, Marco Armiliato, Peter Schneider, Andris Nelsons, Fabio Luisi, Asher Fisch, Yves Abel, 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.
Born and raised in Vienna Clemens Unterreiner also spent his childhood in Graz and Budapest. After he completed his school at the Academic High School he commenced studying law at the University of Vienna. During his studies, he began to train his voice and to deepen his knowledge in music theory and musicology. Since 1998 he started singing lessons among others with Prof. KS Hilde Rössel-Majdan, Prof. KS. Gottfried Hornik, Prof. Helena Lazarska and KS. Wicus Slabbert (KS = singer of outstanding merit), He participated in master classes with Prof. KS. Bernd Weikl, KS. Artur Korn and Prof. KS. Gottfried Hornik. During the year 2000 he was awarded a Bayreuth Festival Scholarship and in 2002 he was a semifinalist at the International Belvedere Singing Competition in Vienna. His extensive repertory includes lyric italian, german and french chivalrous and heroic baritone parts, operetta as well as a wide range of art song repertory including Schubert, Schumann, Strauss, Brahms, Wolf and many more, but also contemporary works of various composers.
He started his carreer at the annual Vienna Festival (Wiener Festwochen) and performed in concert tours in Bulgaria, Syria, Italy, Spain and Germany. He 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 "La Traviata" - Germont, "Fidelio" - Pizarro and "Tosca" - Scarpia and in October 2002 he made his opera debut at the State Theatre in Linz for the European première of "The Voyage" by Philip 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 the première 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. During the summer of 2005 he sang the title role in Don Giovanni at the Heidenheim Opera Festival in Germany and Bartolo in Paisiello's "Barber of Seville". On September 4th 2005 he had his house debut in Puccini´s "Manon Lescaut" where he started his carreer a soloist and ensemble member of the Vienna State Opera. In 2006 he sang Hermann, Schlemihl and Crespél in "The Tales of Hoffmann" and Don Parmenione in Rossini´s "L´occasione fa il ladro". 2007 he was heard as Don Fernando - Minister in "Fidelio" and celebrated with great success his debut as Guglielmo in "Cosi fan tutte". In 2008 he was guest soloist at the Opera Festival of Steyr, where he celebrated as Consul Sharpless in Puccini's Madama Butterfly a great successes. In fall 2008 he debuted with great success also as Consul Sharpless (Italian original version) at the Vienna Volksoper and was listening to since then there as a guest soloist in Carmen, Magic Flute, Rusalka and The Bat. In 2009 he sang with great success Papageno and made his debut as a celebrated Sulpice in the premiere of "La fille du régiment". In 2010 he celebrated as Donner a successful home debut in "Rheingold" at the Wagner - Festival Budapest and sang 2011 a very successful debut at the Royal Opera Copenhagen as Sharpless (Madama Butterfly). In 2012, he sang his house debut as Melot at the Opera House in Nice and made his debut at the Salzburg Festival. He debuted further in the new production of the Vienna State Opera, Gluck's Alceste as high priest / god of the underworld. 2013 he celebrated a brilliant success as Papageno in Mozart's Magic Flute at the Opera de Nice and a highly acclaimed Wolfram in Wagner's Tannhäuser. He also sang back its popular Vienna Faninal at the Vienna State Opera. In April 2013, he opened a Faninal at the gala performance of Rosenkavalier the new opera house in Linz. He sang at the State Opera the new production of Puccini's "La Fanciulla del West" and celebrated in the lead role of the mayor considerable success in the world premiere of the children's opera "Das Städchen Drumherum".
Clemens Unterreiner made his debut in Arabella at the Semperoper in Dresden with Christian Thielemann and rescued the premiere of Hansel and Gretel shortly afterwards as the father - Peter Besenbinder at the Viennese Staatsoper also under the direction of Christian Thielemann. In 2016, he sang the New Year's Eve and New Year's Bat at the State Opera and made his debut at the premiere in the 3 sisters - tri sestri of Peter Eötvös. He also sang Albert in Werther at the Royal Opera House Muscat and sang at the Staatsoper, among others, in Tosca, La Bohéme, Manon, La fanciulla del west and Alceste. For his 10th anniversary at the Opera Klosterneuburg he triumphed as Tonio in Bajazzo and afterwards celebrated at the Vienna Staatsoper as the first Austrian after 34 years a great success as Escamillo in Carmen. In the autumn he sang several song recitals and concerts in the Ehrbarsaal and the Wiener Musikverein and celebrated his debut at the Royal Opera House Muscat as Telramund in Wagner's Lohengrin. He is looking forward to the "Zauberflöte" and „The Bat“ on New Year's Eve at the Staatsoper. Further premieres will be on the agenda at the Vienna State Opera, the St. Margarethen Opera Festival, Steinbacher Philharmonic Weeks Attersee, and a revival of the Rosenkavalier production at the Tokyo State Opera.