Wolff was born in Nice in France to German literary publishers Helen and Kurt Wolff. The family moved to the United States in 1941, and Christian Wolff became an American citizen in 1946. At the age of sixteen he was sent by his piano teacher Grete Sultan for lessons in composition with new music composer John Cage and quickly became a close associate of Cage and his artistic circle, which included fellow composers Earle Brown and Morton Feldman, pianist David Tudor, and dancer/choreographer Merce Cunningham. Cage relates several anecdotes about Wolff in his one-minute Indeterminacy pieces.
Wolff's early compositional work included a lot of silence and was based initially on complicated rhythmic schema[disambiguation needed], and later on a system of aural cues. He innovated unique notational methods in his early scores and found creative ways of dealing with improvisation within his written music. During the 1960s he developed associations with the composers Frederic Rzewski and Cornelius Cardew who spurred each other on in their respective explorations of experimental composition techniques and musical improvisation, and then from the early 1970s in their respective attempts to engage with political matters in their music. For Wolff this often involved the use of music and texts associated with protest and political movements such as the Wobblies. His later pieces often give a degree of freedom to the performers such as the sequence of pieces entitled Exercises (1973-). Some works, such as Changing the System (1973), Braverman Music (1978, after Harry Braverman), and the series of pieces entitled Peace March (1983–2005) have an explicit political dimension responding to contemporary world events and broader political ideals.
Wolff recently said of his work that it is motivated by his desire "to turn the making of music into a collaborative and transforming activity (performer into composer into listener into composer into performer, etc.), the cooperative character of the activity to the exact source of the music. To stir up, through the production of the music, a sense of social conditions in which we live and of how these might be changed."
Wolff's music reached a new audience when Sonic Youth's "Goodbye, 20th Century" featured works by avant-garde classical composers such as John Cage, Yoko Ono, Steve Reich, and Christian Wolff played by Sonic Youth along with several collaborators from the modern avant-garde music scene, such as Christian Marclay, William Winant, Wharton Tiers, Takehisa Kosugi and others.
With his wife Holly, Wolff has four children: Hew, a computer programmer living in Oakland, CA; Tamsen, a professor of Drama and English at Princeton University; Nicholas, a graduate student in Archaeology at Boston University; and Tristram, a graduate student in Comparative Literature at University of California Berkeley.