Pamela Sheyne, who also contributed vocals for the demo. Initial recording of the song was done at the Murlyn Studios, Stockholm, for which Sheyne provided the background vocals with the final recording being done at Sony Music Studios, New York City. In an interview, Birgisson commented on the collaboration with Sheyne saying that: "Pam came up with the title 'Irresistible', and as she started talking about the whole concept we immediately became inspired and began working on the music. You know, when we hear a concept or a title that we like—no matter if it's ours or somebody else's—both Anders and I get a feel for the song's vibe; a feel for whether a keyboard or guitar should be used to give it a certain character, be it upbeat or melancholic. So, when Pam mentioned the title, we immediately came up with the tempo and the whole feeling of the song, and then she came up with the lyrics. There was a really good flow to that song. We played around with the melody, put down the demo, and it was done." Vocals were recorded and engineered by Robert Williams using a Sony C-800G Studio Tube condenser microphone while post-recording editing, via the Pro Tools software, was done by Peter Wade Keusch. Mats Berntoft played the guitar on the track, while Bagge mixed the song. Ted Jensen mastered it at Sterling Sound, New York City. Composition "Irresistible" is a moderately paced R&B song composed in the verse–chorus–bridge form with a play time of three minutes and thirteen seconds. The song draws influence mostly from the dance-pop genre while infusing elements of funk music, and Latin rhythms. The song is written in common time, in the key of G sharp minor. The tempo is ninety-four beats per minute, with a chord progression of G#m–C#m7–E–D#7. Simpson's vocals in the song span over two octaves from the low note of E3 to the high note of D#5. Cashbox Canada commented that Simpson adopts "breathy vocals" for the song, and it has a "gently danceable backing while Chuck Taylor of Billboard noted that Simpson's vocals in the song were "funk-fortified". The Dallas Morning News Teresa Gubbins observed that the track possesses a rat-a-tat-tat beat, similar to "There You Go" (2000) by singer Pink. The song features a string section by Stockholm Session Strings as well as spoken passages by Simpson and a midsection breakdown.