Born in New York City, Feldman became a leading voice in 20th-century classical music through his association with experimental composers such as John Cage, Christian Wolff, and Earle Brown. His early career was defined by his development of graphic notation, which allowed for a departure from traditional rhythmic constraints and fostered a unique, fluid approach to composition.

His signature style is characterized by soft, unfocused pitch shadings, asymmetric patterns, and a generally quiet aesthetic. In his later period, beginning around 1977, Feldman shifted his focus toward works of extreme duration, often pushing the boundaries of endurance and listener perception through repetitive, slowly shifting textures.

Feldman remains a foundational influence on contemporary minimalism and experimental music. His legacy continues to be studied and performed globally, with his notational innovations serving as a critical bridge between mid-century avant-garde practices and modern sound art.