Walker started his professional career with Motherwell in 1984, helping the club to gain promotion before moving to Celtic in the summer of 1987 for a fee of £350,000. His first season at Celtic Park was hugely successful, as the Bhoys won the double in 1987–88, their centenary season, and Walker himself earned a first Scotland cap against Colombia. The following 3 seasons were less fruitful however and by 1991–92 Walker was out of the first team picture. After loan spells with Newcastle United and Bolton Wanderers, he joined the Burnden Park side permanently in 1992. At Bolton, Walker returned to his form of 1988, establishing a prolific partnership with John McGinlay as the Lancashire side earned promotion to the First Division in 1992–93. That same season, he famously scored at Anfield to help the Trottersknock holders Liverpool out of the FA Cup. Walker continued in the same vein the following season until sustaining a serious knee injury against Swansea City. Upon his recovery, Walker was the subject of a surprise bid from Celtic and he returned to Glasgow in 1994. 1994–95 was a mixed season for Walker. On the positive side, he won a Scotland recall and earned his third cap in October, while his Celtic side won the Scottish Cup in May 1995. In between these events though were the negatives, as the Hoops struggled in the League and suffered a shock defeat by Raith Rovers in the League Cup final. Due to the arrival of Andreas Thom in the summer of 1995, Walker was again deemed surplus to requirements at Parkhead and joined Sheffield United for £500,000 in early 1996. Walker's time in the Steel City was relatively productive; his goals tally a respectable 24. Nevertheless, Walker was again to quickly fall from favour, and after brief loan spells at Hibernian, and Raith Rovers in 1998, he ended his career in the lower leagues. This period encompassed short spells with Ayr United, Carlisle United, Partick Thistle, and Alloa Athletic.
Media career
Since his playing retirement, Walker has worked as a pundit for STV on their Scotsport highlights programme, which he became the main presenter of, alongside Grant Stott, due to Jim Delahunt's departure. The programme was axed in May 2008, due to increasing competition from BBC Scotland's Sportscene. Walker is also writing a column for the Glasgow-based Sunday Mail newspaper. In 2007/08, Walker began presenting STV's coverage of the UEFA Champions League, as well the station's UEFA Cupmatches, taking over from Jim White. Walker now regularly features on Sky Sports as a color commentator for Scottish Premiership and Cup games. During the 2015–16 season, Celtic captain Scott Brown criticised Walker, labelling him a "poor man's Gary Neville" in May 2016.
