Walker was born on 9 July 1973 at 3.00am in Sutton-in-Ashfield, Nottinghamshire, weighing 7lbs 13oz. His father, Barry, was employed as a miner before working in an office, while his mother ran her own hairdressing salon. He has a younger sister, Elizabeth. When Walker was eleven years old, his parents divorced, and he continued to live with his mother. Within a year, his father married again to his step-mother, Hilary.
Walker joined Notts County as a trainee in July 1991, but failed to make a first-team appearance and moved to Walsall in August 1993, making his debut in the same month. He went on to make 475 appearances in all competitions for Walsall in eleven years, the most by any goalkeeper for the club and became a cult hero at Bescot Stadium. While at Walsall he was a key player in three promotion seasons, won their Player of the Season award twice and was selected in the PFA Second DivisionTeam of the Yearin 2001. He was awarded a testimonial in the summer of 2003. Walker's popularity proved such that an autobiography was commissioned to coincide with his testimonial season; ghosted by Walsall programme editor, Andrew Poole, it proved to be a relative success with fans of Walsall and of West Ham United. Walker's successes at Walsall included promotion from Division Three in 1995 and from Division Two in 1999 and again in 2001. He was nicknamed "Wacka" by the Walsall fans.
acquired Walker's services from Walsall on a Bosman free transfer in the summer of 2004. Walker, who provided competition for Stephen Bywater, was the second choice goalkeeper at Upton Park but gained a regular first team place within a year of his arrival. Walker gained praise from West Ham fans on saving a penalty taken by Frank Lampard in the League Cup in October 2004, in front of the West Ham supporters' end at Stamford Bridge. However, despite his heroics, the Hammers lost the tie 1–0. Walker helped West Ham win promotion in 2005, but a serious knee injury in the closing stages of the play-off final saw him miss the majority of the 2005–06 season. He made his first appearance since the knee injury, and his Premiership debut at the age of 32, in a 4–2 defeat to Portsmouth in March 2006. He made only two more first team appearances, though collected a FA Cup Final runners up medal as an unused substitute in May 2006. The presence of Roy Carroll and Robert Green as goalkeepers at West Ham during the 2006–07 season meant that Walker's first-team chances were limited; in spite of this, he still remained a popular figure at Upton Park. On 27 November 2008, Walker signed on loan for Colchester United. He made his debut for Colchester on 29 November 2008 in their 2–1 victory against Northampton Town and played 16 times for the club before returning to West Ham. On 3 June 2009, West Ham announced that Walker had been released.
At the start of September 2009, at the age of 36, Walker was signed on a short-term contract by Tottenham Hotspur as a third choice goalkeeper. He was released by Tottenham on 1 July 2010 without making a first-team appearance.
Return to Walsall
On 29 October 2010, Walker re-signed for Walsall, on a short-term contract due to end in January 2011. On 28 January 2011 he extended his contract to the end of the 2010–11 season. On 12 April 2011 Walker made his 500th appearance for the "Saddlers", against Brentford, which ended in a 3–2 win for Walsall. On 8 June 2011, Walker signed a further one-year contract with the club. On 7 January 2012, in a 2–2 home draw with AFC Bournemouth, Walker made his 529th appearance in all competitions for the club, equalling Colin Harrison's appearance record. He broke the record, which had stood since 1981, in an away fixture against Brentford the following week, on 14 January 2012. He kept a clean sheet in a match that finished 0–0. In July 2012, Walker signed a fresh one-year deal with Walsall which saw him working in a player-coach role with the League One club. On 7 February 2013, after making 533 appearances for the club during two separate spells over the past two decades, Walker left Walsall by mutual consent. He had failed to make a first-team appearance during his final season with the club.
