He has a long and well-regarded history as an improviser, known for a masterful yet often understated technique that transforms the soprano saxophone into an electronic-like, textural, or percussive device. He is also known for his ongoing critique of improvisational practice, which has brought influential concepts and stylistic components into the practice as a whole. While Rainey has worked with numerous improvisers globally, he is best known for his solo work, Nmperign (with trumpeter Greg Kelley), and his direction of the improvising large ensemble, The BSC. Rainey also works in the realm of electronic and algorithmic composition. In 2013, Rainey was awarded the prestigious Pew Fellowship in the Arts for his work in these areas.