The tune was composed for a radio broadcast in October 1930 and was originally titled "Dreamy Blues". It was "the first tune I ever wrote specially for microphone transmission", Ellington recalled. "The next day wads of mail came in raving about the new tune, so Irving Mills put a lyric to it." Renamed "Mood Indigo", it became a jazz standard.
The main theme was provided by Bigard, who learned it in New Orleans, Louisiana from his clarinet teacher Lorenzo Tio, who called it a "Mexican Blues". Ellington's arrangement was first recorded by his band for Brunswick on October 17, 1930. It was recorded twice more in 1930. These recordings included Arthur Whetsol (trumpet), Joe Nanton (trombone), Barney Bigard (clarinet), Duke Ellington (piano), Fred Guy (banjo), Wellman Braud (bass), Sonny Greer (drums). Ellington blended muted trumpet, muted trombone, and clarinet.
Ellington took the traditional front-line--trumpet, trombone, and clarinet--and inverted them. At the time of these first three recordings in 1930, the usual voicing of the horns would be clarinet at the top (highest pitch), trumpet in the middle, and the trombone at the bottom (lowest pitch). In "Mood Indigo" Ellington voices the trombone right at the top of the instrument's register, and the clarinet at the very lowest. This was unheard of at the time, and also created (in the studio) a so-called "mike-tone"—an effect generated by the overtones of the clarinet and trombone (which was tightly muted as well). The "mike-tone" gives the audio-illusion of the presence of a fourth "voice" or instrument. Ellington used this effect in "(In My) Solitude" (1932), "Dusk" (1940), and many other pieces throughout his career. The Ellington band performed and recorded the song continuously throughout its 50 years, both in its original form and as a vehicle for individual soloists.
"Mood Indigo" is featured in the films All Night Long (1962), Bait (1954), The Continental Twist (1961), The Cotton Club (1984), Curtain Call (1999), Divine Secrets of the Ya-Ya Sisterhood (2002), Frances (1982), Harlem Nights (1989), Hart's War (2002), Julia (1977), Keep On Keepin' On (2014), The Legend of Bagger Vance (2000), Paris Blues (1961), Pitch People (1999), Renacer (1981), Rough Cut (1980), The Untouchables (1987), Up In the Air (2009), The White Countess (2005) and White Men Can't Jump (1992). It can also be heard in the TV movie Relentless: Mind of a Killer (1993) and in the miniseries Come In Spinner (1990) and Mildred Pierce (2011), as well as in episodes from two HBO series created by David Chase: "Walk Like a Man" from The Sopranos (1999-2007) and "El Dorado," the series finale of Boardwalk Empire (2011-2014).