Theresa Horejsi was born into a family of musicians in 1999. Starting with the violin, she often took part in the Jugend Musiziert competition and gained experience in youth orchestras and chamber music ensembles at an early age. She discovered the viola through her family. Before starting her studies, she completed a preparatory course at the music school in her home town of Mülheim an der Ruhr. From 2018, she studied at the Cologne University of Music and Dance in the class of Matthias Buchholz and finished her studies at the Haute École de Musique de Lausanne in 2024 with Tatjana Masurenko. In September 2023, she took part in the renowned ARD Music Competition.
She was a trainee with the Duisburg Philharmonic Orchestra at the Deutsche Oper am Rhein and then with the Sinfonietta de Lausanne.
As a chamber musician, she has worked with Jörg Widmann, the Minguett Quartet, Harald Schoneweg, Gregor Schwellenbach, Rio Arai, Robert Kulek, Daniel Haefliger and Peter Bruns among others.
She received important influences from Martin Outram, Tabea Zimmermann, Hartmuth Rode, Noémie Bialobroda, Gerard Caussé and Frédéric Kirch among others.
She also took part in recordings for the Arte film TRANS - I Got Life, which was broadcast on television in September 2023. She has also been principal violist in the Swiss Youth Symphony Orchestra (SJSO) from 2023-2025. In 2024 she took up a 3rd solo position in the St. Gallen Symphony Orchestra. From September 2025 she joins l’Orchestre de la Suisse Romande as a tutti player.
