Delfeayo Marsalis is the son of pianist Ellis Marsalis and brother of Branford and Wynton Marsalis, and Jason. He attended the New Orleans Center for Creative Arts, and had from the age of thirteen trombone lessons. In Tanglewood he studied classical trumpet, and in 1983 he led the New Orleans Philharmonic Orchestra Gordon Jacobs on trombone concerto. For his presentation of Alessandro Marcello's Sonata No. 6, he received the Outstanding Performance Award from the Jefferson Performing Arts Society.
From 1982, he studied trombone and studio production at the Berklee College of Music. He produced, inter alia, about 75 albums with Harry Connick, Marcus Roberts, Spike Lee and his brothers, some of whom had reached a Grammy Nominations. In 1996 he received the 3M Visionary Award.
As a trombonist, Marsalis toured with musicians such as Art Blakey, Abdullah Ibrahim, Elvin Jones, Slide Hampton, Ray Charles, Art Blakey's Jazz Messengers, and Max Roach. He also leads a modern jazz band with whom he recorded three albums.
He composed music for the ABC series Moon over Miami, the documentaries Streetcar Mysteries and 112th & Central and the productions of the New Orleans Ballet of Tennessee Williams' Streetcar Named Desire and Glass Menagerie.
In 1997, he composed for the Summer Day Theatre The Musical Luther. He then founded the Uptown Music Theatre for the musical theater training for children and adolescents 8-18 years, with whom he worked five musicals in three summers. In 2005, he earned a Masters degree in Jazz Performance at the University of Louisville. In the 2007/2008 season, he led concerts with the Minnesota Orchestra, among others Compositions of Duke Ellington on.