The Bee Gees wrote this love song at the Château d'Hérouville in France - the "Honky Chateau" where Elton John recorded three albums in the early '70s. When they arrived to record songs for Saturday Night Fever, they found it had been neglected - the studio worked, but the grounds were a mess. This gave them focus because they had little reason to leave the studio. There was a beautiful room with a piano where their keyboard player, Blue Weaver, would play. One day, he played as Barry Gibb worked out "How Deep Is Your Love." In the documentary How Can You Mend A Broken Heart, Weaver explained how it came together: "We went into a room at the Chateau. Chopin had stayed there, so every time I looked at this piano I envisioned Chopin playing. I sat down at the piano and thought of his 'Prelude In E-flat,' and I knew Barry could sing in E-flat. Through the stained-glass window came a beam of sunlight, and Barry sang, 'I know your eyes in the morning sun.'"

The American singer Yvonne Elliman was supposed to record this song for Saturday Night Fever, but Robert Stigwood, who produced the movie, insisted the Bee Gees perform it themselves for the soundtrack. Elliman did sing "If I Can't Have You," which was written by the Bee Gees and included on the soundtrack. That song was also a #1 hit in the US.

In Daniel Rachel's The Art of Noise: Conversations with Great Songwriters, Robin Gibb explained the unique sound he and Barry created by combining their voices: "If you listen to 'How Deep is Your Love' you think it's a single voice but it's me and Barry singing in unison, which produces a nice sound, as it does on 'New York Mining Disaster.' There's a sound that we do, it's almost like a single voice, but it isn't, and it's not double-tracked, it's two voices together. It's something that we've done a lot."