The instrumental and vocal track was recorded under the production of Brian Wilson on October 27, 1967. Initially Wilson had planned to give this song and "Time to Get Alone" to a band called Redwood (later to be known as Three Dog Night) as Danny Hutton was a friend of Wilson. Hutton laid claim to inspiring the title for "darlin'", it being frequent in his vocabulary at the time. Redwood only got as far as recording a guide vocal before Mike Love insisted that Brian focus his attention on producing work for the Beach Boys. Accompanied by piano, bass, tambourine, strings, and horns, Carl Wilson sings lead vocals.
The "Darlin'" single, backed with "Here Today", was issued by Capitol Records in the United States in December 1967. The single peaked at the number 19 position on the Billboard charts, but it placed at number 10 on the Cash Box sales chart. Radio station playlists indicated high popularity in Santa Barbara (#1), Los Angeles (#2), Baltimore and Norfolk (#4); Washington, Boston, Honolulu (all #5); San Diego, Fresno, Portland, Milwaukee, Louisville (all #6); Vancouver (#7), Toronto (#9), and New York (#14).
In the United Kingdom the single was issued in January 1968 with the B-side "Country Air". The single peaked at the number 11 position. In New Zealand the single peaked at the number 10 position. In Sweden it placed number 15, and in the Dutch single charts the song peaked at number 21.
The song was initially written as "Thinkin' 'Bout You Baby" by Wilson and Love years earlier, and was first recorded in April 1964 and released as a single two months later by Sharon Marie—a previously unrecorded teenager who had informally auditioned for Wilson and Love by singing opera standards after a Sacramento Beach Boys concert—with production by Wilson himself. The song later appeared on the 2004 compilation Pet Projects: The Brian Wilson Productions.