Mariano Horak studied singing and musicology at the University in Bratislava and at the Tchaikovsky Music Conservatory in Kiev.For a few years, after graduation, Horak sang as a baritone in different opera houses in Germany and Switzerland. In 1984 he founded Lyric Department in the “Caecilia” Agency in Zürich, and has been a director there since then. He worked with many great artists including Mirella Freni, Christa Ludwig, Teresa Berganza, Lucia Popp, Peter Schreier, Piero Cappuccilli, Nicolai Ghiaurov, and many more.
Mariano Horak always showed great interest for young artists, he wanted to discover them and with focused and artistic guidance help them to achieve their international carrier. He has discovered many great artists such as Violeta Urmana, Julia Kleiter, Anna Goryacova, Ausrine Stundyte, Stephan Gould, Johan Reuter, Antonio Poli, Goran Jurić and many others.
Horak is often invited to be a jury member or observer in many different international singing competitions to keep in track with the new coming generation of young singers. In June 2015 he opened his own agency named Ammann-Horak Agency which is situated in Zürich.