The song's success was responsible for relaunching Mercer's career as a songwriter, which had stalled in the mid-1950s because rock and roll replaced jazz standards as the popular music of the time. The song's popularity is such that it has been used as a test sample in a study on people's memories of popular songs.
Comments about the song have noted that it is particularly reminiscent of Mercer's youth in the Southern United States. An inlet near Savannah, Georgia, Johnny Mercer's hometown, was named Moon River in honor of him and this song.
Mercer and Mancini wrote the song for Audrey Hepburn to fit her vocal range. Initially, the lyrics started, "I'm Holly, like I want to be / like Holly on a tree back home ..."; however, they were later changed to fit the theme of the film Breakfast at Tiffany's.
Although an instrumental version is played over the film's opening titles, the lyrics are first heard in a scene where Paul "Fred" Varjak (George Peppard) discovers Holly Golightly (Hepburn) singing them, accompanied by her guitar, on the fire escape outside their apartments.
There was an eruption of much behind-the-scenes consternation when a Paramount Pictures executive, Martin Rackin, suggested deleting the song from the film immediately after a very successful San Francisco preview. Hepburn's reaction was described by Mancini and others in degrees varying from her saying "over my dead body" to her using somewhat more colorful language to make the same point.
Hepburn's version was not included in the original movie soundtrack. Instead, an album version recorded by Mancini and his chorus was released as a single and became a number 11 hit. In different versions, Joel Whitburn's Top Adult (Contemporary) Songs reported the song as a #3 or #1 easy listening hit, due to unpublished charts in Billboard. Only months after Hepburn's death in 1993 her version was released on an album titled Music from the Films of Audrey Hepburn
"Moon River" was a hit single for Jerry Butler in late 1961, reaching number 11 on the Billboard Hot 100 chart in December, two weeks before Mancini's recording reached the same spot. Meanwhile across the Atlantic, South African singer Danny Williams had a hit version of the song that reached number one in the UK in the final week of 1961. Although Andy Williams never released the song as a single, his LP Moon River and Other Great Movie Themes, released in the spring of 1962, was certified Gold in October 1963 for sales grossing over $1 million.
On October 4, 2006, Canadian turntablist Kid Koala (Eric San) reinterpreted the song at Picnic Electronik in Montreal. Dedicated to his parents, Kid Koala's version features an extended violin solo he performs live by playing notes from the song's instrumental section at different pitches on four turntables. He also performed this piece while opening for Deltron 3030 (October of 2013) in Eugene, OR.
In February and March 2013 New Zealand artist Neil Finn (of Crowded House) and Australian artist Paul Kelly performed a series of collaborative concerts on their Goin' Your Way Tour which included "Moon River" as one of the final numbers in their set list. A gig at the Sydney Opera House Concert Hall was recorded for a live album, Goin' Your Way, which was released in November that year as a 2× CD, Blu-ray and DVD. The title of the albums comes from a phrase in the song's chorus: "Wherever you're goin', I'm goin' your way".
^ abBartlett, James C., and Snelus, Paul; Snelus, Paul (September 1980). "Lifespan Memory for Popular Songs". The American Journal of Psychology (University of Illinois Press) 93 (3): 551–560. doi:10.2307/1422730. JSTOR1422730.