"Giant in My Heart" is an electropop and house track sung in an emotive falsetto tone and features a combination of scat-singing, a pounding 808 and softer synth-led sections.
"Giant in My Heart" garnered positive reviews from contemporary music critics, who commended the song for its sonic similarities with Kiesza's debut single "Hideaway" and the singer's strong vocal performance.
"Giant in My Heart" marked Kiesza's second consecutive top five single in the United Kingdom and has also had success in Germany and Belgium where it peaked at numbers 11 and 12 respectively.
Kiesza has performed "Giant in My Heart" on American television show Jimmy Kimmel Live!, and the song has been covered by English singer Florrie.
[1] In an interview with KAMP-FM's Carson Daly, Kiesza elaborated on the anonymous male vocalist featured in "Giant in My Heart", "I've never actually met him.
[3] "Giant in My Heart" was digitally released as a single and four-track remixes extended play (EP) in the United Kingdom on August 8, 2014.
Digital Spy's Amy Davidson awarded the song a three (out of five)-star rating and stated that it successfully showcased "the sheer power" in Kiesza's vocal abilities.
[7] Vice journalist Ryan Bassil felt that "Giant in My Heart" would become "absolutely massive",[14] while Tina Campbell of Metro said the song is "sure to get you heading to the dance-floor.
"[16] Michael Baggs of Gigwise felt that "Giant in My Heart" proved that Kiesza was not a one-hit wonder and wrote, "It's pretty damn good, and suggests she has a big future ahead of her.
[17] Robbie Daw of Idolator felt that "Giant in My Heart" was a "fantastic" follow-up to "Hideaway" and stated, "[the song is] a nice gesture toward fans who got on board with her retro sound, given that debut singles can often be misleading representations of an artist's overall material these days.
"[13] Marissa Muller of CBS Radio felt that "Giant in My Heart" built on the "diva vocals" and "lose yourself-beat" that made "Hideaway" a success.
Following the low-budget clip for predecessor "Hideaway", Kiesza chose to make a short film for "Giant in My Heart" that would be different in style and content in comparison to the former.
[12] While after hours, he returns to his apartment and resorts to an alter ego of a drag queen as a coping mechanism for his occupational stress and being bullied and pushed around at work.
[15] Idolator reviewer Robbie Daw noted, "Kiesza takes the backseat in this one by playing the part of a club performer who gives a little inspiration to our troubled hero (ine)".
[31] CBS Radio reviewer Marissa Muller commended the video for being a definite departure from the visual for "Hideaway", she also praised Kiesza's "great dance sequence in theme with the song's '90s vibes.
Andre Paine of the London Evening Standard positively reviewed the performance writing, "Her stirring vocals over the insidious groove of 'Giant in My Heart' were as bold as her choreography.
Idolator's Bradley Stern praised the version, writing, "[Florrie] turns the bouncy House anthem into a truly gorgeous, gentle guitar-led production — that is, before she starts riffing loudly against a lively guitar strum.