Ellington called his style and sound "American Music" rather than jazz, and liked to describe those who impressed him as "beyond category", including many of the musicians who served with his orchestra, some of whom were themselves considered among the giants of jazz and remained with Ellington's orchestra for decades. While many were noteworthy in their own right, it was Ellington that melded them into one of the most well-known orchestral units in the history of jazz. He often composed specifically for the style and skills of these individuals, such as "Jeep's Blues" for Johnny Hodges, "Concerto for Cootie" ("Do Nothing Till You Hear from Me") for Cootie Williams and "The Mooche" for Tricky Sam Nanton. He also recorded songs written by his bandsmen, such as Juan Tizol's "Caravan" and "Perdido" which brought the "Spanish Tinge" to big-band jazz. After 1941, he frequently collaborated with composer-arranger Billy Strayhorn, who he called his alter-ego.

One of the twentieth century's best-known African-American celebrities, Ellington recorded for many American record companies, and appeared in several films. Ellington and his orchestra toured the United States and Europe regularly before and after World War II. Ellington led his band from 1923 until his death in 1974. His son Mercer Ellington took over the band until his death in 1996. Today the band performs under the direction of Barry Lee Hall, Jr.