It was released for digital download and streaming by Atlantic Records and Warner Music Group on 24 July 2020 as a standalone single.

An acoustic version of "Lighter", which credits Henderson and features a new verse by KSI, was released on 28 August 2020 alongside an accompanying music video.

"Lighter" received positive reviews from music critics, who commonly praised the song's catchiness and KSI's energetic verse, and it was dubbed "one of the hits of the summer".

"Lighter" was one of the UK's best-selling songs of 2020 and it has been certified platinum by the British Phonographic Industry (BPI) for exceeding sales of 600,000 units in the country.

Dawe explained, "I've known of KSI for a long time and I've been quite a fan of his work... His music recently that's started to come out, the quality [of it has] been really good...

[4] Dawe could not be present at the recording studio due to COVID-19 pandemic travel restrictions, but he spectated the session via Zoom.

The lyrics give inspiration to those who are struggling through a breakup, heartbreak, or even through losing a toxic person in their life, and feeling better despite the hard times.

[3] The staff of Sport Playlists similarly described "Lighter" as an "anthemic slice of feel-good dance music" that was "written with summer in mind".

[11][12] The cover art shows a photo of Dawe and KSI that was taken on the set of the song's music video shoot, in front of a red and white background.

[18][19] Dawe, KSI and Henderson performed "Lighter" on BBC One's Top of the Pops New Year Special, which aired on 31 December 2020.

The staff of Sports Playlists liked the song's "infectious chorus" and they praised KSI's "memorable verse", which "[punctuates] the track’s bubbling, sugary melodies".

Evans praised KSI's "[evolution] as a lyricist" and found it "refreshing to see that some serious thought [had been] put into [his] words and their alternative meanings".

[21] Oliver Tryon of CULTR noted that "KSI's signature rapping... [allows] for an injection of rhyming energy that allows for a refreshing sound overall".

"[8] Robin Murray of Clash called the song "a clinical banger for those looking to unload [COVID-19] lockdown energy" and proclaimed that it "could well be a summer smash [hit]".

[26][27] The music video opens with a cast, comprising Dawe, KSI, S-X and Window Kid, playing poker.

[29] It earned the highest new entry on the UK Singles Chart, debuting at number four, becoming both artists' first song to reach the top five.

[36][37] On 1 January 2021, "Lighter" was certified platinum by the British Phonographic Industry (BPI) for sales of 600,000 track-equivalent units in the UK.