"This is My Song" was intended for the film A Countess from Hong Kong, which Charlie Chaplin wrote and directed. Chaplin saw his film as a throwback to the shipboard romances that were popular in the 1930s, and wrote "This Is My Song" with the intent of evoking that era. To reinforce the evocation, Chaplin was determined to have Al Jolson sing the song—so determined that he only accepted the information that Jolson had died on 23 October 1950 when shown a photograph of Jolson's tombstone. Ultimately, the song would be featured in the film only as an instrumental.

After being disillusioned with regard to Jolson, Chaplin considered having "This Is My Song" recorded by Petula Clark, who had a home in Switzerland near his residence. Clark's husband and manager Claude Wolff—who at the time was with Clark in Reno, Nevada—received a copy of "This Is My Song" in September 1966, and liked the song which Clark felt had special potential for success in France. However, Clark's regular collaborator Tony Hatch was not impressed with the song, and refused Wolff's invitation to arrange it for Clark to record. French label Vogue Records then commissioned a then successful French arranger Jacques Denjean whose work was judged unsuitable by Wolff. Ultimately, Vogue's U.S. distributor Warner Bros. records sent Ernie Freeman who flew to Reno to prepare for the song's recording session which was to be produced by Sonny Burke at Western Studios in Los Angeles. Clark recorded the song not only in English, but in French as "C'est Ma Chanson" (lyrics by Pierre Delanoë, who also felt the song a poor choice for Clark), German as "Love, So Heisst Mein Song" (lyrics by Joachim Relin) and Italian as "Cara Felicità" (lyrics by Ciro Bertini). Clark did not even wish to record the song in English, because she disliked the deliberately old-fashioned lyrics, which Chaplin refused to modify; however, after the translated versions of the song had been recorded, some time remained on the session, and Burke coaxed Clark to use this to record Chaplin's lyrics. The recording session featured the backing of the Wrecking Crew

The first recording of "This Is My Song" was made by Harry Secombe, with Wally Stott responsible for arranging and conducting. Secombe himself found the lyrics risible; several takes were necessitated due to his bursting into laughter when he tried to sing the line: "I care not what the world may say". Despite the eventual UK release of Clark's version as a single, "This Is My Song"'s appeal was strong enough to sustain two versions high on the chart. Secombe's version debuted at number 44 on 25 February 1967 (the second week Clark's version was number one) to rise as high as number two on the chart dated 1 April (which featured Clark's version at number eight). (Clark's previous UK #1 song, "Sailor", had also had a rival version, in that instance by Anne Shelton, which had reached the Top 10. Wally Stott, who'd regularly produced Clark for the Polygon label in the early 1950s, had also overseen the Shelton recording.) Secombe's version of "This Is My Song" was included on the album Secombe's Personal Choice, an April 1967 release whose chart peak of #6 in May 1967 bests that of both the Petula Clark albums which parented the song. Besides selling over 300,000 units in the UK, Secombe's version of "This Is My Song" also became a hit in Australia (#6), Ireland (#20) and South Africa