Since 2012/13, the Lucerne-born tenor has been a member of the ensemble of the Deutsche Oper am Rhein Düsseldorf/Duisburg. His roles include the Astrologer in Rimsky-Korsakov's "The Golden Cockerel", Brighella in "Ariadne auf Naxos", the Witch in "Hansel and Gretel", Pedrillo in "The Abduction from the Seraglio", Eisenstein in "Die Fledermaus" and Almaviva in "Il barbiere di Siviglia". Guest engagements have taken him repeatedly to the Ludwigsburger Schlossfestspiele, the Styriarte Graz and the Wiener Festwochen, as well as the Lucerne Festival.
At the Accademia di Santa Cecila in Rome, he sang the Evangelist and the tenor arias in Bach's "St Matthew Passion" under Antonio Pappano. In May 2019, he made his role debut as Loge in "Das Rheingold" in Gelsenkirchen. The George Enescu Festival in Bucharest engaged him for various roles in "Carmina Burana" and the Dresden Philharmonic for Jaquino in a CD recording of "Fidelio". In addition, he sang Kudrjasch in a new production of "Katya Kabanova" in Düsseldorf and Wagner/Loriot's "Der Ring an einem Abend" in Munich/Gasteig, KKL/Lucerne, Liedhalle Stuttgart, Philharmonie Berlin, Meistersingerhalle in Nuremberg, Kuppelsaal in Hanover and the Festspielhaus Baden-Baden.
At the Budapest Wagner Days in 2021/22, he appeared as Mime in "Das Rheingold" and "Siegfried", and at the Zurich Opera House in March/April 2023 as Monostatos in "Die Zauberflöte". At the Deutsche Oper am Rhein, Cornel Frey sang in 2023/24 in such diverse roles as Goro ("Madama Butterfly"), Pong ("Turandot"), the Witch ("Hansel and Gretel"), Lindoro ("L'italiana in Algeri"), Almaviva ("Il barbiere di Siviglia"), Prince Andreas Stephan ("Märchen im Grandhotel"), Ari in "The Comedian Harmonists", and on tour as Mime/Loge in a revival of "Der Ring an einem Abend".
Concert engagements included "Paulus" in Bochum and the "St John's Passion" (Evangelist and arias) in Bern. In 2024/25, he sang Piet the Pot in a new production of "Le Grand Macabre" in Wiesbaden, Verdi's Requiem in Lüdenscheid, the "Christmas Oratorio" in Altenberg Cathedral, David in "Die Meistersinger von Nürnberg" at the Budapest Wagner Days, etc.