Born in Warsaw in 1947, he studied sound engineering and composition with Tadeusz Baird, Andrzej Dobrowolski, and Włodzimierz Kotoński at the Music Academy in Warsaw. He took part in the Summer Courses of New Music in Darmstadt (1974, 1976). Since 1973 he has collaborated with the Polish Radio Experimental Studio. In 1978 he worked for the Center of the Creative and Performing Arts in Buffalo.
He is the co-founder of creative groups, including the kew Composers' Group (1973-76), 'Cytula Tyfun da Bamba Orkiester' (1981), the Independent Electroacoustic Music Studio (1982-84), 'Light from Poland' (1985-87), 'Freight Train' (since 1986), the Ch&K Studio (since 1989) and the European Improvisation Orchestra (since 1996).
Apart from works for acoustic instruments, Knittel has also written computer music, created performances, built sound installations and played in improvised music ensembles.
He has performed his music at numerous concerts and festivals of new music in most of the European countries, Asia, and North and South America, including concerts devoted exclusively to his music (Barcelona, Budapest, Cracow, Moscow, Sao Paulo, Warsaw). He has given lectures on new music in Alicante, Barcelona, Boston, Budapest, Philadelphia, Munich, Prague and Viitasaari.
As journalist and critic, he contributed to the Tygodnik Literacki periodical and freelanced for Polish Television (the weekly arts feature and the Music Department).
He served as Vice-chairman of the Polish Section of the iscm (1989-92). He was the director of the International Contemporary Music Festival 'Warsaw Autumn' (1995-98). In 1999 he was elected President of the Polish Composers' Union.
His honors include the Solidarity Prize for the String Quartet written in tribute to Father Jerzy Popiełuszko (1985). He was also awarded the Award of the Foundation for Contemporary Performing Arts in New York (1998).

Selected works (since 1980): Norcet 1 and Norcet 2, music for tape (1980), Three Studies for piano (1980), 29 staves for chamber orchestra (1980-81), Starry Sky for percussion ensemble (1982), Man-Orchestra I for any instruments and tape (1982); Black Water, White Water, Old Stream for instruments and tape (1983), That, which is for any five instruments and piano (1983), Four Preludes for piano (1983), String Quartet (1984-85), Lapis, music for tape (1985), Old Style Pieces, music for tape (1985), Three Cassettes for three performers (1986), Poko, music for tape (1986), Brother John's Struggle for flute, trombone, guitar, violin and percussion (1987), Three Songs Without Words for soprano and tape (1987), Nibiru for string orchestra and harpsichord (1987), Histoire I for tape (1988), Histoire II for clarinet, piano, synthesizer and tape (1988), Histoire III for harpsichord and tape (1989), Man-Orchestra II for computers and objects (1989), JingleJungle for voices and computers (1989), Borders of Nothing for computers (1990), Man-Nature, a collection of 16 graphical compositions (1991), Homage to Charles Ives for flute, oboe, clarinet, bassoon, piano, percussion, viola and double-bass (1992), 14 Variations by Piotr Bikont and Krzysztof Knittel on 14 Variations by Edwin Morgan on 14 Words by John Cage for voices and computers (1992), Instant Reactions for voice, instruments, synthesizer and computer (1992), Negev for percussion instruments and synthesizer (1993), Between for piano and tape (1993), Sonatas da camera (Nos. 1-11) for instruments, voice, synthesizers and sampler (1993-2002), Homage to Barbara Zbrożyna for synthesizer and sampler (1997), surface en rotation, music for tape (1997), Out of the depths have I cried unto Thee, O Lord..., psalms for choir and electronic sounds (2000), Spiegelverkehrte Reise for soprano, actor and electronics (2000), El maale rahamim... for choir and symphony orchestra (2001), Norwid Songs for soprano and piano (2001), Trio for optional melodic instruments (2001).
Stage works: detour, musical event for speaker, cello, piano, percussion and tapes (1974), Glückpavillon for Cathy, music theatre for tuba and tape (1978), Woman's Voice (after poems by Rafał Wojaczek); ballet (1980), Light, monologue for actress (1981), Satan in Goray, libretto after Isaac Bashevis Singer (ballet, 1993), Der Erwählte, libretto after Thomas Mann (ballet, 1995), Awakenings, libretto after Oliver Sachs (ballet, 1998), The HeartPiece - double opera (together with John King (1999).
Installations: The Legs (1993), Radio Sculpture (1994), Passage (1994).