Niblock's music is an exploration of sound textures created by multiple tones in very dense, often atonal tunings (generally microtonal in conception) performed in long durations. The layering of long tones only very slightly distinct in pitch creates a multitude of beats and generates complex overtone patterns and other fascinating psychoacoustic effects. The combination of apparently static surface textures and extremely active harmonic movement generates a highly original music that, while having things in common with early drone-based Minimalism, is utterly distinct in sound and technique. Niblock's work continues to influence a generation of musicians, especially younger players from a variety of musical genres.[1]

Niblock's compositional process often begins with recordings of single, absolute tones played by a specific musician with the breathing and attack and decay edited out. Such collaborations have been crucial to his composing life, and the range of musicians with whom he has worked include David Gibson, in the cello works of the 1970s); Petr Kotik, Susan Stenger, and Eberhard Blum, on Four Full Flutes; Rafael Toral, David First, Lee Ranaldo, Thurston Moore, Susan Stenger, and Robert Poss on Guitar Too, for Four (G2,44+1x2); Ulrich Krieger, Carol Robinson, Kaspar T. Toeplitz, and Reinhold Friedl, on Touch Food; Dave Soldier and the Soldier String Quartet on Five More String Quartets, Early Winter; and many others. In the past decade he has produced several works for orchestra: Disseminate, Three Orchids (for three orchestras), Tow for Tom (for two orchestras), and 4 Chorch + 1, the latter a commission for the Ostrava Music Days 2007 for chorus and orchestra with solo baritone (Thomas Buckner). The premieres of all these works have been conducted by Petr Kotik.

In performance, live musicians may play, wandering through the audience changing the sound texture through reinforcement of or interference with the existing tunings. Simultaneously, Niblock generally accompanies performances by presenting his films and videos (often those from The Movement of People Working series, or computer-driven, black-and-white abstract images floating through time). These performances fall into two types: (1) an installation of several hours' duration, with the music pieces played consecutively, with a long loop of several hours of work before repetition, and with multiple images that are shown simultaneously; or (2) a performance, with several simultaneous works of music and film, usually lasting between one and three hours. In these performances Niblock generally projects three (or more) film images simultaneously, on large screens three to four meters wide. The films are 16mm and color. The music is produced from stereo or quad tapes, with four or more speakers in the corners of the space. His more recent video pieces are played individually or with several simultaneously, using large video monitors.