In the mid-1940s, he led a major big band that became associated with modern jazz trends. The group is often remembered as a launching point for influential musicians moving from swing toward bebop.

Eckstine’s trademark was a warm baritone with clear diction and a relaxed sense of swing. He was equally at home with jazz phrasing and popular ballad singing, which helped broaden his audience beyond jazz clubs into mainstream venues.

He is widely regarded as one of the great male vocalists of his era and an important figure in the transition from the big-band age to modern jazz. His recordings and performances influenced later singers who blended jazz nuance with pop accessibility.