One was a hit for Three Dog Night. Chuck Negron of Three Dog Night names One as his favorite of the group's recordings.

Harry Nilsson said that he was inspired to create the song when he heard a busy signal on the telephone.

"Donkey" (Eddie Murphy) sings a line from "One" in the beginning of the animated film Shrek 2. The soundtrack for the film based on the hit TV show "The X-Files" includes a cover of One by Filter. During filming, David Duchovny (as "Fox Mulder") ad-libbed the line, "One is the loneliest number" so the producer commissioned the recording of One for the soundtrack - the only song specifically recorded for the film's soundtrack.