Jeff Parker began playing guitar at an early age, and extended his studies from 1985 at the Berklee College Of Music. He also studied with George Garzone, playing totally improvised music. Subsequently, he gigged with Antonio Hart and others before moving to Chicago in 1991. At the time, this was considered to be an unusual step because many of his contemporaries were making New York their home base. Although he has indicated that he never intended staying there, that it was a way station on the road to New York where he could establish himself free from orthodox external influences, Chicago proved to be very fertile ground. In the city, he teamed up with cornettist Robert Mazurek and drummer Chad Taylor to form the Chicago Underground Trio and the same three musicians sometimes augmented to form the Chicago Underground Orchestra.
Another group from the collective is Isotope 217, in which Parker is joined by Mazurek and trombonist Sara P. Smith. With the Chicago Underground Trio, Parker's form of musical expression is couched in a dynamically exhilarating mélange of hard bop, free jazz and non-jazz forms. Similarly eclectic are other groups with which Parker was associated in the 90s, among them one of the leading post-rock bands, Tortoise, the New Horizon Ensemble, Uptightly, the Aesop Quartet and Tricolor. He also regularly associated with other contemporary Chicago-based artists, including Fred Anderson, Lin Halliday and Ken Vandermark. By the end of the 90s, Parker's reputation was thoroughly established and in addition to his activities on the improvised music scene, he also performed and sometimes recorded with rock musicians.