Henri Pousseur was born in Malmédy (Belgium) on 23 June 1929. He studied music at the Conservatoire de Liège and Bruxelles from 1947 to 1953, but considers himself to be mainly self-taught, i.e., student of all musical styles. From 1950 he was active in the international avant-garde music scene (dodecaphonic, serial, electronic, aleatoric music), side by side with Boulez, Stockhausen, Berio, and others. In 1954 he married Théa Schoonbrood with whom he had four children: Isabelle (1957), Denis (1958), Marianne (1961) and Hélène (1965).
From 1960 Pousseur took an independent artistic stance "refusing the refusal" of historical experience (a stance referred to by some as "tabula rasa"), and made efforts to bridge the dualism of ancient and modern, "scholarly" and populist etc. This watershed (which in his eyes is not a renunciation of his deep bond to Webern, rather a fulfillment of it) marks the beginning of his cooperation with Michel Butor, which has continued ever since. (Among their twenty-odd works are Votre Faust, 1961–68, La Rose Des Voix, 1982, Le Sablier Du Phenix, 1994, etc.)
Pousseur taught in Germany, Switzerland, and the United States, and then at the University and Conservatory of Liège from 1970 onwards, where he also founded the Centre de recherches et de formation musicales de Wallonie. As director of the Conservatory from 1975, he brought a fresh wind to musical pedagogy and, in a larger context, to the musical life of his city. Subsequently he was appointed to supervise the establishment of the Institut de Pédagogie musicale de Paris (from 1983 to 1987) now integrated into the Cité de la Musique as its Centre de ressources. Here he founded the magazine Marsyas, which has published 40 issues to date. Again in the realm of music education, Pousseur, himself active at both university and conservatory, introduced the licence en communication musicale. This course of studies employs teachers from both institutions and is open to students of both, thereby form an interdisciplinary link between the two institutions. In 1994 Pousseur retired and moved with his wife to Waterloo, in order to be closer to Bruxelles and his family. Until 1999 he was composer-in-residence at the K.U.L. (University of Leuven).
Pousseur has composed some 150 works of different dimensions for different functions. He is author of numerous articles and books and holds honorary doctorates from the the Universities of Metz and Lille.