During his studies at the Žilina Conservatory Ondrej Olos became assistant conductor of the Symphony Orchestra of the Conservatory, and during his studies at the Janáček Academy of Music and Performing Arts in Brno he was awarded by Leoš Janáček Prize for the realization of the chamber version of the opera The Cunning Little Vixen by Janáček in Chamber Opera of the Janáček Academy of Music and Performing Arts in Brno.
He is regular guest conductor in various Czech and Slovak orchestras, such as Radio Symphony Orchestra in Bratislava, Prague Chamber Philharmonic, Brno Philharmonic, Moravian Philharmonic Olomouc, Bohuslav Martinů Philharmonic Orchestra Zlín and others. As an excellent pianist he regularly cooperates with violinist Milan Paľa.
In a season 2011/2012 he assisted the realization of the opera Jenůfa by Janáček in France and in the Slovak National Theatre in Bratislava; in a season 2012/2013 he realized two one-act operas Gianni Schicchi and Il Tabarro by Puccini in the Košice Opera. In the Opera of the Slovak National Theatre he cooperated (as assistant conductor of Tomáš Hanus) on realization of the opera The Makropulos Case by Janáček, which he ended up conducting (in a season 2015/2016).