Mercer Ellington was born in Washington, DC. He is the son of Edna Thompson and of the famous composer, pianist, and bandleader Duke Ellington. A rising composer and arranger, Mercer Ellington was only 18 when he had written and composed his first piece titled "Pigeons and Peppers". Mercer Ellington's most famous composition, "Things Ain't What They Used To Be", was featured over the years by the Ellington band. However, some of Ellington’s lesser-known pieces such as "Moon Mist” and “Jumpin' Punkins" had considerable merit as well.

Ellington attended New College for the Education of Teachers at Columbia University (in what year?), and later attended New York University, and The Juilliard School. In 1939, he started to lead his own bands.