The song was co-written by Minogue, Maegan Cottone and its producer Sky Adams, and was inspired by celestial imagery and intergalactic themes, in contrast to the parent album's traditional and contemporary disco sound.

[1] During her tour, she was inspired by a segment influenced by the disco aesthetic and Studio 54, and she realised that her creative path would be "heading straight back to the dance floor" with a disco-themed album.

During the lockdown, Minogue worked remotely from her London home, experimenting with different software and engineering tools such as Logic Pro and GarageBand.

[3] Minogue wrote "Supernova" with American singer-songwriter Maegan Cottone and producer Sky Adams, who also collaborated on other Disco tracks.

[5] Minogue was also inspired to give "Supernova" a "slightly spacey" sound to distinguish it from traditional and contemporary interpretations of disco music throughout the parent album.

[10][11]   According to Beats Per Minute writer Mathew Barton, the track's composition consists of a "fabulous concoction of electric piano, throbbing bassline, strings, and better vocal production that enhances rather than detracts from the rest of the song.

[7] CJ Thorpe-Tracey of The Quietus described it as an homage to Minogue's collaborations with Stock, Aitken, and Waterman, "plus the song throws tons of random planet names and space-science words at the wall and quite a few of them stick.

Neil Z. Yeung of AllMusic praised the song as a "intergalactic frenzy", while Lisa-Marie Ferla of The Arts Desk called it "robotic funk".

[7] Grindr staff praised Minogue's vocal deliveries, comparing the vocoder effects to Daft Punk, and wrote, "Kylie really rises to the challenge with a gutsy and lusty performance that underlines what an underrated pop vocalist she is.

"[23] Variety writer Andrew Barker described the song as a "rough patch" with "its heavily processed, monotone vocal tracks, is crying out for a more postmodern, Gaga-esque flamboyance than Minogue is willing to provide..."[11] According to Jeffrey Davis of PopMatters, the song and album track "Miss a Thing" were overproduced with "manic sounds and manipulated vocals".