Knight's first book of photographs, Skinheads, was published in 1982, when he was a 24-year-old photography student at Bournemouth and Poole College of Art and Design. He was then commissioned by i-D editor Terry Jones to create a series of 100 portraits for the magazine's fifth anniversary issue. As a result of those black-and-white portraits, his work caught the attention of art director Marc Ascoli, who commissioned Knight to shoot the 1986 catalogue of avant-gard Japanese designer Yohji Yamamoto in collaboration with renowned graphic designer Peter Saville. Since this first foray into fashion photography, he has shot both editorial and advertising projects for clients including Alexander McQueen, Audi, Calvin Klein, Christian Dior, Jil Sander, Lancôme, Levi Strauss, Martine Sitbon, Mercedes-Benz, Royal Ballet, Royal Opera House, Swarovski and Yves Saint Laurent.
In November 2000, Knight launched SHOWstudio.com, an online fashion broadcasting company committed to pioneering, live fashion media. SHOWstudio.com has broken new ground with its experimental interactive projects, films and live performances. Its collaborations with influential cultural figures, from Björk, Boy George, Kate Moss and John Galliano to Leigh Bowery, Heston Blumenthal and Antony & the Johnsons, are broadcast live, in real time on the SHOWstudio.com website.
Knight has won awards for his editorial work for Vogue, Dazed & Confused, i-D, The Face, W Magazine, Another Magazine, Arena Homme + and Visionaire, as well as for fashion and advertising projects such as the 2004 edition of the Pirelli Calendar. He has shot album covers for Elvis Costello and the Attractions, Björk,Boy George, David Bowie, Kylie Minogue, The Style Council, Paul Weller, Gwen Stefani, Seal, ABC and Massive Attack, and has produced Nicknight (1994), a twelve year retrospective, and Flora (1997), a series of flower pictures, both published by Schirmer Mosel.
Knight's work has been exhibited at such international art institutions as the Victoria & Albert Museum, Saatchi Gallery, the Photographers' Gallery and Hayward Gallery. In 1993, he also produced a permanent installation, Plant Power, for the Natural History Museum in London.