Born in New York, Ruiz was a child prodigy who performed at Carnegie Hall at the age of eight and studied with Mary Lou Williams. While still a teenager, he played with saxophonists Frank Foster and Joe Henderson and trumpeters Cal Massey and Freddie Hubbard.

In the 1970s, he spent time in the bands of saxophonists Rahsaan Roland Kirk and George Coleman. He also led his own groups and played with Tito Puente, Dizzy Gillespie, and Charles Mingus.

Ruiz was one of the few musicians with equal facility in straight-ahead jazz and Latin jazz. "There's a lot of people who dabble with both worlds," trombonist Steve Turre told the AP last month. "But very few can authentically deal with both."