The song was penned by the artists, Eskeerdo, Ed Sheeran, Marcus Lomax, Mike Hawkins, Sam Martin, Toby Green, and William Spencer Bastian, the latter four producing it alongside the DJs.

Featuring dance, EDM, electro-pop, hip hop, and house music, the song's lyrics celebrate the moment of having a good time and the memories of crazy nights.

[2] Atlantic and Warner released "Big" for digital download and streaming in various countries on 12 February 2021 as the lead single from Ora and Imanbek's collaborative extended play Bang (2021).

[10] A writer for the Official Charts Company, Jack White, labeled it a "lavish party anthem and a sure-fire floorfiller" and complimented the collaboration as well as the vocal performances of Ora and Gunna.

[4] Jannik Pesenacker of Dance-Charts correspondingly praised the collaboration for delivering a "strong radio song", with particular commendation for the harmony between the instrumental and vocals of Ora and Gunna.

[7][11] Writing for Fun Radio, Nassim Aziki named it a "good vintage" and responded that "the pop side of [Ora] combined with the electro of [Guetta] works perfectly well".

[12] While reviewing Bang, Farrell Sweeney from Dancing Astronaut hailed the song for boasting a "heavy-hitting lineup" and regarded it as the "contender for project's radio favorite".

[26][27][28] To accompany the release, a music video for "Big" premiered on Guetta's official YouTube channel on 12 February 2021, which is a tribute to Ora's Albanian and Imanbek's Kazakh heritages.

[35] The music video begins with an aerial shot capturing a vehicle transporting a group of individuals, leading to a solo performance by Ora on a pipeline located within a block of residential buildings.

[6] She further explained that "it is undoubtedly an analogy of what Ora's family must have experienced when they moved to England: the nature of your place of origin, in contrast to a world of cement, after arriving in the suburbs of a big city".