Rex Stewart (1907–1967) was an American jazz cornetist best known for his work with the Duke Ellington orchestra.

After stints with Elmer Snowden, Fletcher Henderson, Horace Henderson, McKinney's Cotton Pickers, and Luis Russell, Stewart joined the Ellington band in 1934. Ellington arranged many of his pieces to showcase Stewart's half-valve effects, muted sound, and forceful style.

Stewart co-wrote "Boy Meets Horn" and "Morning Glory" while with Ellington, and frequently supervised outside recording sessions by members of the Ellington band. After eleven years Stewart left to lead his own groups. He also toured Europe and Australia with Jazz at the Philharmonic from 1947 to 1951. From the early 1950s on he worked in radio and television and published highly regarded jazz criticism. Jazz Masters of the Thirties is a selection of his criticism.