freelance cellist specialising in contemporary and avant-garde music performance, he studied at the Chopin Music Academy of Music in Warsaw. He has won prizes at the Krzysztof Penderecki International Contemporary Chamber Music Competition in Cracow and Witold Lutosławski International Cello Competition in Warsaw. He has appeared at festivals such as Warsaw Autumn, Musica Polonica Nova, Polish Modern Music Festival of Premieres in Katowice, Poznań Music Spring, as well as Audio Art and Ad Libitum. He is a regular member of the Warsaw Cellonet Group and Chain Ensemble. 

As a member of Netherlands-based Cello Octet Amsterdam (formerly Conjunto Ibérico), he toured Europe, Brazil, Mexico, and the USA in 1998–2008. His contemporary music recital CD Cellovator was released in 2008. Thanks to scholarships from the City of Warsaw and Polish Minister of Culture and National Heritage, he has composed a cycle of etudes for solo cello (Pretudes, 2012) and created the audiovisual compositionsDłubak Soundsystem (2012) and AVC (2016). In a duo with violinist Anna Kwiatkowska, Mikołaj performs contemporary and new music. He encourages new music and has premiered many works dedicated to him. In 2021, he obtained a PhD from the Chopin University of Music in Warsaw.