A backup band or backing band is a musical ensemble that typically accompanies a single artist who is the featured performer. The situation may be a live performance or in a recording session, and the group may or may not have its own name, such as "The Heartbreakers" (the band of Tom Petty), or "Bob Wills and his Texas Playboys" in the 1930s. Often, backup bands contain sidemen who are skilled but not known to the public; these musicians may be replaced or substituted at any time without noticeable impact on the performance.

A number of cohesive stand-alone groups of musicians have emerged from the shadow of the starring celebrity (whom they are backing) to achieve a stature of their own. An example is the Eagles in 1971, emerging from being the backing band for Linda Rondstadt. Another example is The Band, a group who backed Bob Dylan on his world tour in 1966, his first tour with electric instruments.

A backing band may also be a cadre of elite studio musicians who serve as a house band for major studios. The same musicians may perform on records by a number of different artists. Examples are Stax Records' band, Booker T. & the M.G.'s; Detroit's The Funk Brothers; and Nashville's A-Team.