Denis Cohen was born in France in 1952. He trained at the Conservatoire de Paris (CNSMDP) from 1969 to 1979, earning honors in composition, harmony, counterpoint, and piano accompaniment. He continued his piano studies with Jean Fassina and played percussion for five years. He won the silver medal at the Finale Ligure Piano Competition in Italy in 1977, and was a resident at the Villa Médicis in Rome from 1982 to 1984. Despite this extensive musical training, he considers himself to be a self-taught composer and conductor, the two parallel vocations that have brought him the most renown.

Denis Cohen's compositions are fairly unique in the world of French contemporary music, notably because he has always rejected the placement of serial and spectral music in opposing camps, and because his music has such distinct Germanic features (particularly in its consciously organic formal conception). Karlheinz Stockhausen and Bernd Alois Zimmermann are notable influences in this regard, as may be heard in his earlier compositions, such as Transmutations, written in 1980.

After a series of instrumental pieces in his early years of composing, Cohen turned to vocal compositions, such as Cantate in 1982 and La Cassure des nuages in 1983. In them, the transparent texture of his earlier works gives way to densely layered compositions, such as in Sprache of 1988. In the early 1990s, after a period of densely written works in the 1980s, compositions such as Doppi versi alla luna for voice, clarinet, and percussion or Il sogno di Dedalo heralded the birth of a new sensibility that might be described as "mediterranean."

Considering the dangers of connotation inherent in using traditional instruments in the context of modern musical language, Cohen enjoys "subverting" instrumental sounds with electronics; his piece Jeux (1984-1988) reflects his natural interest in the junction of the piano and IRCAM's 4X synthesizer.

Cohen made his first foray into opera with Ajax-Opéra interrompu (1983-1984), an exploration he made with certain conditions attached, given the long history stretching from Monterverdi to Zimmermann and without giving in to any "turning back to" that the genre naturally implies. The vocal and symphonic cycle that came out of his reflections on the possible relationships between the theatrical and the musical was begun in 1986 and includes purely orchestral pieces, such as Close Islands and Étude pour le Poème. Sprache, written for four singers bearing texts in five languages, a narrator, and an orchestra, is an "imaginary painting" where the paradigms of the opera's characters are displayed and spatialized, brought to the stage as images. This trilogy was followed by a pentalogy in which the orchestra journeys to the pit, and each opera in this gestating cycle "examines" a national paradigm linked to each of the five languages in Sprache. A new opera, l’Homme trouvé (1992-1995), was added to this cycle, with a libretto co-written with Jean-Claude Carrière.

His more recent works include Erinnerung, (a commission from the IRCAM-Centre Pompidou), which premiered in June 2009, performed by the Quatuor Arditti during the Festival Agora Paris.

In parallel, Denis Cohen is an orchestra conductor, a practice which nourishes his constant quest to establish links between composing, formal design, and the sounding result of musical pieces. He served as conductor of the Ensemble intercontemporain in 1980, and as assistant conductor in 1981-1982. After this, he was a regularly invited conductor for ensembles, orchestras, and choirs in Europe, Australia, and Israel (including for the Nouvel Orchestre Philharmonique de Radio France, Ensemble Orchestral de Paris, Ensemble Modern in Frankfurt, Orchestre du Conservatoire national supérieur de musique de Paris, Ensemble l'Itinéraire, Ars Nova, Alternance, 2e2m, Asko d'Amsterdam, and Elision in Melbourne).

Since 1999, Denis Cohen has taught orchestration at the Conservatoire national supérieur de Paris, after teaching master classes in conducting there in 1994 and 1995. He was also a professor at the Institut d'études politiques de Paris from 1999 to 2001. He writes as a critic and published a book of interviews with the musicologist Michel Rigoni in 2008, and his writing reflects his position in the world of contemporary composing and his resolutely modernist stance.

His works are published by Nodus.

• Silver medal at the Finale Ligure Piano Competition in Italy in 1977
• Fellowship from the French Ministry of Culture in 1979 (for Trames)
• Research fellowship from the French Ministry of Culture to study inharmonicity at the IRCAM in 1980
• Fellowship from the French Ministry of Foreign Affairs for research in the Stanford University computer music department in 1982
• Villa Médicis fellowship in 1982
• Prix de Rome in 1982 for a two-year residency at the Villa Médicis
• SACEM Albert Wolff prize for Cantate in 1983
• SACEM Hervé Dugardin prize for lifetime achievement in 1988