Musically, the song combines chillwave, disco, electroclash, and synth-pop with elements of techno, alternative pop, and new wave.

In November 2017, Swift released her sixth studio album, Reputation, accompanied by its lead single "Look What You Made Me Do", which contained lyrics referencing karma.

[4] Beginning on September 21, 2022, Swift began unveiling the track-list in a randomized order through her short video series on TikTok, called Midnights Mayhem with Me.

[10][11] In April 2023, American trade publication Hits reported that "Karma" is set to be serviced to US radio as the album's third single, following "Anti-Hero" and "Lavender Haze".

[15] On May 24, Swift and Ice Spice announced via social media a remixed version of "Karma" featuring the latter and posted the cover artwork.

[16] The same night of the release, May 26, Swift brought out Ice Spice during her Eras Tour at her stop in East Rutherford, New Jersey for their first live performance of the Karma remix.

[17] Its original announcement was met with backlash from some social media users, who interpreted the remix as "damage control" after Swift was criticized online for reportedly dating the English singer-songwriter Matty Healy, who had laughed at "racist" jokes made by the American comedians Adam Friedland and Nick Mullen about Ice Spice during their podcast.

[21] During the Eras Tour, beginning with the concert in Buenos Aires, Argentina on November 11, 2023, Swift frequently changed the lyrics to Karma to reference her relationship with Kansas City Chiefs player Travis Kelce.

[35][36] She does not seek revenge on her enemies and instead lets the universe takes its course; while karma makes her detractors suffer for their wrongdoings, it bolsters her for her good deeds.

"Karma" was written by Swift, Jack Antonoff, Mark Anthony Spears, Keanu Torres and Jahaan Akil Sweet.

[40] Rolling Stone named it the fourth best song of 2022; they called it an "album-defining hit" that combines Swift's "mastermind" lyrics and the "sleekest, most flexible" production.

[29] American Songwriter listed it as one of the 24 best songs of 2022, and called it the "sleeper hit" of Midnights; praise was directed towards Swift's lyrical approach, the "effervescent" chorus, and Antonoff's production.

[43] In a mixed review of the remix, Shaad D'Souza of Pitchfork opined that the collaboration was a "clash of sensibilities" that diminished the appeal of the original version.

The remix also marked Ice Spice's third career top-10 entry and highest-charting song, and made Midnights the first album since the Weeknd's After Hours (2020) to produce three top-two singles.

[73] She premiered it on May 26, 2023, at the first East Rutherford show of her Eras Tour (2023), where she was joined by Ice Spice as a surprise guest to perform the song.

[74] The video features heavy digital effects, incorporating "cosmic or celestial" imagery, and packed with Easter eggs recalling some of Swift's earlier albums.

[73] For example, she appears as a comical "Dorothy" on a yellow brick road featured in a Wizard of Oz-themed storybook; as a woman dressed in turquoise, backed by an enormous photo of her cat Olivia curled up sleeping; and as a green "giantess" covered by forest and mountain, whereas Ice Spice is in a "heavenly cloud formation.