At the age of 25 Walker shot his first fashion story for Vogue, and has photographed for the British, Italian and American editions ever since. He has also contributed to Harpers Bazaar, W, i-D and Vanity Fair magazines, and advertising campaigns for brands such as Yohji Yamamoto, Guerlain and Dior Parfums.
His first major show was held at the Design Museum in London in 2008, coinciding with the publication of his first monograph Pictures. In November 2008 Walker received the Isabella Blow Award for Fashion Creators from The British Fashion Council and, in May 2009, he received an Infinity Award from The International Center of Photography, New York. In 2012 Tim opened a major mid-career retrospective at Somerset House in London which marked the launch of his second book Story Teller (Thames and Hudson, 2012). In 2019, he was the subject of a major solo exhibition at the Victoria and Albert Museum, the largest show the museum has ever held for a living artist. Walker's work is held in the permanent collections of both the Victoria and Albert Museum and the National Portrait Gallery in London.