John Janssen, a native of the Netherlands with German-Belgian roots, sang as a soprano soloist in his father's church choir from the age of six. In addition to studying piano at the Maastricht Conservatory, he studied singing with Hans Günther Grimm. His first engagement took him to the music theater in Gelsenkirchen, where he built up an impressive repertoire within five years. In 1982, Wolfgang Sawallisch hired him at the National Theater of the Bavarian State Opera in Munich, where he played the title roles in Rossini's Barber of Seville and Mozart's Don Giovanni, as well as Count Almaviva in The Marriage of Figaro alongside Margaret Price, Lucia Popp and Hermann Prey under the direction of Wolfgang Sawallisch. In the opening premiere of the Munich Opera Festival in 1983 (which is also available on CD), he played the role of Adriano in Richard Wagner's Rienzi alongside René Kollo and Cheryl Studer. For his interpretation of this role he received the Festival Prize of the Bavarian State Opera and was voted Singer of the Year in 1984. Further roles there were Guglielmo (Cosí fan tutte), Fluth (The Merry Wives of Windsor), Schaunard (La Bohème), Malatesta (Don Pasquale), Papageno (The Magic Flute) and others. John Janssen sang with the following conductors: Wolfgang Sawallisch, Carlos Kleiber, Hans Zöbeley, Miguel Gomez-Martinez, Ferdinand Leitner, Georges Prêtre, Uwe Mund, Will Humburg, Donald Runnicles, Roderick Brydon, Bernhard Klee and many others. Guest appearances have taken him to the Hamburg State Opera (Harlekin/Ariadne and titlerole Eugen Onegin), the Berlin State Opera (titlerole Don Giovanni), the Vienna State Opera (Schaunard/La Bohème - titlerole Jakob Lenz), Drottningholm Slottsteater (titlerole Don Giovanni) and the opera houses of Frankfurt (titlerole Eugen Onegin), Wiesbaden (Wolfram/Tannhäuser), Copenhagen (Wolfram/Tannhäuser), Bern (titlerole Don Giovanni and Wolfram/Tannhäuser) - Basel (Graf/Intermezzo) and St. Gallen (titlerole Don Giovanni), Teatro Alesandria and Settembre Musica Turin (titlerole Jakob Lenz and Vincent) and others. As Jakob Lenz in the homonymous opera by Wolfgang Rihm, he appeared in the Gelsenkirchen production at several festivals in Europe and also received great praise for it on a tour of South America. As an oratorio singer he has performed in Würzburg (St. Matthew Passion), Mantua (Fauré Requiem), in the basilicas of Vézelay (arias/St. John Passion) and Autun (Mozart and Brahms Requiem), in the Teatro La Fenice in Venice (Carmina Burana), Duomo di Cremona (Brahms Requiem) and in several places and various oratorios in the Netherlands, Belgium, France and Italy.