Barbara Lewis first recorded "Baby I'm Yours" in a January 8, 1965 Atlantic Recording Studios (NYC) session directed by Bert Berns with the producer credit assigned to Lewis's manager Ollie McLaughlin. The session for the track featured George "Teacho" Wiltshire conducting his orchestra, whose personnel included Clark Terry and Dud Bascomb (trumpets), Jimmy Cleveland and Tony Studd (trombones), Frank Haywood Henry (baritone sax), Charlie Brown (tenor sax), Paul Griffin (piano), Bill Suyker (guitar), Jimmy Lewis (bass), Gary Chester (drums), and Artie Butler (percussion/ handclaps); the harmony background vocals on the track were provided by the song's composer, Van McCoy, singing with Kendra Spotswood
Barbara Lewis has stated that Van McCoy wrote "Baby I'm Yours" specifically for her. When she first heard the demo for "Baby I'm Yours" Lewis disliked the song — she has suggested that she actually was daunted by the high quality of the vocal, by McCoy himself, on the demo  — and at the original session "I didn't really put 100% into my vocal performance" hoping that Atlantic would shelve the track as sub-par. "Ollie [McLaughlin] told me 'Barbara, we're gonna have to go back to Detroit and dub you in. We gotta do your vocals over. You're just not giving like you should on the song.' We did several takes [in Detroit] and he was wondering 'How am I going to get this girl to give? She's so hard-headed.' He said 'You know, Barbara, Karen can sing that song better than you.' That was his little daughter. And it pissed me off. I did one more take, and that was the take that they selected."  It has also been reported that Lewis dubbed her vocal in a Chicago studio. 
Released in April 1965, Lewis' "Baby I'm Yours" enjoyed staggered regional success exemplified by the single reaching #1 in Detroit as early as June 1965 and peaking at #4 in Chicago that August: the national peak of the single was #11 achieved on the Hot 100 in Billboard dated August 21, 1965. "Baby I'm Yours" afforded Lewis a #5 R&B chart hit.
The first UK recording of "Baby I'm Yours" was made by the Paramounts at Abbey Road Studios in the summer of 1965; however the track went unreleased until their 1998 compilation release The Paramounts at Abbey Road 1963 to 1970. A higher-profile act also on the Columbia [UK] roster, Peter and Gordon, had the UK hit version of the song, released October 15, 1965 to reach #19 UK. The Peter and Gordon version was recorded in an Abbey Road session produced by Norman Newell and featuring Big Jim Sullivan on guitar.Peter Asher — who was partnered with Gordon Waller as Peter and Gordon — would recall: "We did 'Baby I’m Yours' because I loved the original Barbara Lewis record."
"Baby I'm Yours" is unique among Peter and Gordon singles as their sole collaboration with arranger Tony Osborne, who took over from the duo's original regular collaborator Geoff Love (subsequent to "Baby I'm Yours" Peter and Gordon regularly collaborated with arranger/conductor Bob Leaper). Also in deference to the US success of the Barbara Lewis version, Capitol Records (Peter and Gordon's US label of release) did not issue the duo's "Baby I'm Yours" single; the Peter and Gordon US single release concurrent with their UK "Baby I'm Yours" single release was "Don't Pity Me", a composition by the duo which peaked at #83. "Baby I'm Yours" was the first Peter and Gordon UK single not be released concurrently in the US.
Jody Miller recorded "Baby I'm Yours" with producer Billy Sherrill1 in a June 16, 1971 session at the Columbia studio in Nashville for inclusion on the album He's So Fine, entitled for Miller's current Top Ten C&W remake of the Chiffons' 1963 #1 hit.
Miller's recording of "Baby I'm Yours" featured the Jordanaires chorale. Impressed by the 1968 Tammy Wynette hit "Stand by Your Man", Miller had contacted that track's producer Billy Sherrill in the hopes of reviving her own flagging recording career. After Look at Mine — Miller's first album in Sherrill's charge — generated two Top Twenty C&W hits in 1970, Sherrill opted for a new musical direction for Miller, who recalls: "He said I didn't phrase my words like a country singer, so we took some old, sexy pop songs and put in a little boppy steel guitar." Issued September 1, 1971 as the second single off He's So Fine, "Baby I'm Yours" reached #5 C&W and #21 Adult Contemporary and afforded Miller her fifth and final Hot 100 showing with a Hot 100 peak of #91.
Elliot's version was produced by Lewis Merenstein and arranged/conducted by Benny Golson. The album was Elliot's debut for RCA Victor who insisted on "Baby I'm Yours" release as the lead single over Elliott and Merenstein's choice: "That Song", a new song by Bill Dean, which would be given single release in April 1972. Neither "Baby I'm Yours" or "That Song" afforded Elliot an appearance on a Billboard chart. Elliot's "Baby I'm Yours" charted on the Canadian Adult Contemporary hitlist, peaking at #18.
In May 1976, a disco remake of "Baby I'm Yours" was released by Linda Lewis, who in 1967 had chosen Lewis as her professional surname in honor of Barbara Lewis, the original singer of "Baby I'm Yours".
Recorded subsequent to Lewis' 1975 album Not a Little Girl Anymore, and not included on her next album release Woman Overboard (1977), "Baby I'm Yours" was included as a bonus track on the 2001 CD release of Not a Little Girl Anymore. The song reached #33 in United Kingdom charts.
The song was issued as a single in March 1978 with "God Knows", a track from Boone's Midstream album, as its flip side. Peter Noone, the co-writer of "God Knows", has alleged "['God Knows'] was originally intended to be the A-side. But the record company chickened out and went with [the] cover of 'Baby I'm Yours' instead." Boone's "Baby I'm Yours" peaked at #33 C&W while on the Hot 100 the track peaked at #74 and on the Easy Listening it reached #14, both in a tandem ranking with "God Knows".
Cher remade "Baby I'm Yours" for the soundtrack of her 1990 film vehicle Mermaids. Cher's version was arranged to replicate Barbara Lewis' hit, and was produced by Peter Asher, who as a member of Peter and Gordon had had the UK hit of "Baby I'm Yours". The song was not featured in the film but was selected as the lead single from the soundtrack for release in the UK and Europe after the US single release "The Shoop Shoop Song" — which as remade by Cher had played under the film's closing credits — fell short of the Billboard Top Thirty. "Baby I'm Yours" failed as a single; its only apparent charting was in the UK at #89 and its estimated global sales tally is 100,000 units "The Shoop Shoop Song" was released in the spring of 1991 with "Baby I'm Yours" as the B-side, and spent five weeks at #1 in the UK and achieved Top Ten status in several European countries as well as Australia and New Zealand. (Coincidentally the precedent charting single to the Linda Lewis 1976 UK hit remake of "Baby I'm Yours" had been the first major UK hit version of "The Shoop Shoop Song", entitled "It's in His Kiss".)
A French-language rendering of "Baby I'm Yours" entitled "Je T'appartiens" was a 1965 single release by Pierre Lalonde and was included on Lalonde's 1966 album release Louise. (This is an exceptional use of the title "Je T'appartiens" which is generally understood to refer to the French-language original of "Let It Be Me".)