Karol Mossakowski started playing the piano and organ with his father at the age of three. After his musical studies in Poland with Elżbieta Karolak and Jarosław Tarnawski, he took organ, improvisation and composition lessons at the Paris Conservatory as a pupil of Olivier Latry, Michel Bouvard, Thierry Escaich, Philippe Lefebvre and László Fassang.