Jon Hendricks helped to originate vocalese, which is an art form of adding lyrics to existing instrumentals and replacing instruments with vocalists. He is also considered to be one of the best scat performers. Jazz critic and historian Leonard Feather called him the "Poet Laureate of Jazz". Al Jarreau has called him "pound-for-pound the best jazz singer on the planet - maybe that's ever been".
After his service in the Army during World War II, Hendricks attended the University of Toledo as a pre-law major. Just as he was about to enter the graduate law program, his G.I. benefits ran out, which forced him to choose a different career path. Recalling that Charlie Parker had encouraged him to come to New York two years earlier to look him up, Hendricks took him up on his offer and moved there and began his singing career. In 1968, he moved his family to London, England to further his solo career and so his five children could receive a better education.