Written by Mitch Allan, Audra Mae, Kara DioGuardi, and Jason Evigan, the song is an uptempo synth-pop track produced by Greg Kurstin.

Directed by Marc Klasfeld, its accompanying music video features scenes of various downtrodden people and their process of finding love again.

[8] Sonically, USA Today's Brian Mansfeld remarked that the record serves as sonic defibrillator, starting with a jolt of melody, its rhythms shifting a couple times before finally settling into its steady pulse;[9] while Idolator's Bradley Stern described its production as Top 40 radio-friendly and remarked that the track sees Clarkson's pulse raising while falling in love above kicky drums, guitars and hints of synths.

"Heartbeat Song" was written by Mitch Allan, Audra Mae, Kara DioGuardi, and Jason Evigan in a two-day session writing camp.

[11] In January 2015, Clarkson revealed a set of clues for the single, posting the words "Proof of life and Dr. Dre #TheNextEpisode (sic)".

[7] Reviewing for Rolling Stone, Jon Dylan gave the song a three-and-a-half star rating, describing it as a "warm, fuzzy snuggle-fest.

"[19] In his midweek review for Spin, assistant editor Brennan Carley wrote that the song is "a Kurstin production that sparkles with new-found passion" and said Clarkson sings a lyric of the chorus with a bubblegum snap.

[20] Reviewing for Time, Nolan Feeney wrote that "Heartbeat Song" as more of a celebration of that than a hungry comeback, reminding listeners of what Clarkson has so reliably provided over the years, with just a few souped-up adjustments.

[25] Digital Spy rated this song with 2 stars out of 5 and concluded by describing it: "ruthless in its pursuit of earworm status, and like it or not it'll find itself lodged in the inner vestibules of your brain.

[42][43] Upon its premiere, the video had received a generally positive response, with mild criticism targeting a scene depicting a couple kissing through the opposite seating sides of a bench.

[23][42] In his coverage for Spin, Carley remarked that there are some surprisingly deep moments tracing the journey from loss to happiness in the video.

Music, senior editor Wendy Geller wrote that despite the video's concept may sound hokey, but the idea that life can change from dark to light in an instant (couple with Clarkson's buoyant vocals) is irresistible.

Clarkson performed the song in a medley with "Since U Been Gone" and "Stronger (What Doesn't Kill You)" on the season three finale of La Voix in Montreal on April 12, 2015.

All tracks are written by Kara DioGuardi, Audra Mae, Jason Evigan, Mitch AllanCredits adapted from the "Heartbeat Song" metadata.