Mansell partnered with American filmmaker Darren Aronofsky and composed the scores for his films Pi, Requiem for a Dream, The Fountain, The Wrestler, Black Swan, and Noah.

He provided the scores for the Ben Wheatley films High-Rise, Happy New Year, Colin Burstead, Rebecca, and In the Earth.

[3] Inspired by David Bowie's performance of Starman on the television series Top of the Pops, he started to play guitar at the age of nine.

[6] After the band was dropped by RCA, PWEI were signed in 1994 to Nothing Records, a label owned by Trent Reznor of Nine Inch Nails.

[8][6] Following PWEI's break-up in 1996, Mansell moved to New York, where he hoped to start a solo career, but struggled creatively.

[12] Aronofsky was unaware of Mansell's previous work with Pop Will Eat Itself, however the two men bonded over their love of hip hop and their belief that "film music at the time was terrible.

[6] Both "Lux Aeterna" and "Requiem for a Tower" have been used in multiple forms of media, including the film trailers for The Da Vinci Code, I Am Legend, Sunshine and Babylon A.D.; trailers for the video games Assassin's Creed and Lord of the Rings: Return of the King; advertising campaigns for such products as Canon PowerShot cameras, Molson Canadian beer; and on television such as in the series America's Got Talent, So You Think You Can Dance as well as a promo spot the series Flash Forward.

Mansell also provided the music for Wheatley's subsequent works Happy New Year, Colin Burstead (2018) and Rebecca (2020) and In the Earth (2021).

[6][21] Mansell's film scores have been sampled by such musical artists as Lil Jon, A$AP Rocky, Bastille and Paul Oakenfold.

[11] Some of his influences include Philip Glass, Trevor Jones, David Holmes, and bands such as Death in Vegas, Mogwai and Unkle.

[22] This deal brought his catalogue of more than 650 original pieces, including his Pop Will Eat Itself work, under a single umbrella for the first time.