Upon graduation in 1994, Walker worked as a freelance photographic assistant in London before moving to New York City as a full time assistant to Richard Avedon. When he returned to England, he initially concentrated on portrait and documentary work for British newspapers. At the age of 25 he shot his first fashion story for Vogue, and has photographed for the British, Italian, and American editions, as well as W Magazine and LOVE Magazine ever since.
Walker staged his first major exhibition at the Design Museum, London in 2008. This coincided with the publication of his book‘Pictures’ published by teNeues.