Jan Klusák studied composition with Jaroslav Ridky and Pavel Borkovec at the Academy of Performing Arts (1953 - 57) in Prague. Since then he has been a freelance composer, theatre and film actor, prose-writer and author of libretti for his own operas.

As a composer, his starting point was Neo-classicism (I. Stravinsky, S. Prokofjev, I. Krejci). Since the autumn of 1959 he started to compose for Libor Pesek's Chamber Harmonic Orchestra (Pictures for 12 Wind Instruments, Four Small Voice Exercises on Texts by F. Kafka, 1st Invention). This gave Klusak the impulse of new creative orientation towards the then New Music, and during the sixties he has been shaping his individual method of composing (particularly in the series of inventions for various combination). He got to grips with the dodecaphony and serial techniques of the Second Viennese School but he has also acknowledged his indebtedness to A. Bruckner and G. Mahler as his favourite masters.

Klusak's masterpiece from this period of time was the highly acclaimed Variations on Mahler's Theme (1962). Astrology and some magic practices are known to have played also a part in the formation of his style, while the composer himself described his method as neo-Platonic. During the sixties Klusak also did a great deal of work in film - as a composer of film music as well as directly as an actor. After August 1968 he was marginalised by the communist regime. At this time, however, he also found some sort of artistic satisfication in collaboration with the satirical theatre of Jara Cimrman. He was further developing his own individual form of invention and in 1975 created another milestone work in the form of his 3rd String Quartet.

After the Velvet Revolution in 1989 Klusak became a public figure, taking on various roles in the world of Czech music, including those of President of the music division of the Arts Society (Umelecka beseda), Vice President of the Czech Council for Music, member of the National Theatre Council, he was also a member of the Arts Council of the Music Faculty of the Academy of Performing Arts, of the Prague Spring Festival Commitee and in some other organizations. He was recipient of a "Classic 1995" Award for his work in composition and for his Fifth String Quartet in particular.