Walker was selected for Kent's first-team for the first time during the team's 1993 pre-season tour of
Zimbabwe. Against a Zimbabwean 'B' team, he scored 23
not out and 16 in a drawn match. Despite the promise shown on the tour, Walker would not play for the first-team for another fifteen months. His
List A cricket debut came on 17 July 1994, in a
Sunday League match against
Worcestershire. In nine matches that season, Walker averaged 23.37. In
first-class cricket, Walker had three seasons where he finished with a
batting average of over fifty: in
1996,
2004 and
2006. 1996 saw Walker hit the highest score of his career to date, on his way to 606 runs at an average of 60.60. Against a Somerset attack without
Andy Caddick, Walker compiled 275
not out in nine-and-a-half hours before his captain
Trevor Ward declared the innings at 616/7.
The Daily Telegraph's
Christopher Martin-Jenkins wrote of the innings: "It was an innings of style and substance, memorable for powerful driving through the off-side and hearty pulling whenever a persevering but ordinary Somerset attack became impatient with line and length and tried to extract a spring in the pitch which simply was not there." It remains the highest score by a Kent batsman at the
St Lawrence Ground. Despite the talent he had shown during his innings against Somerset, he found the next few seasons difficult. In an interview with
All Out Cricket magazine, he said "I’d had a bit of first team cricket, and was dropped and managed to work my way back into the team in the second half of the year but just couldn’t get it right." For four seasons, between 1997 and 2000, Walker consistently averaged in the mid-twenties, scoring just one century in the process. Since then, he has scored over one thousand runs in a season on three occasions. Walker's most productive season in terms of run-scoring was
2006, in which he scored 1,419 runs at the average of 61.19. In the game against
Lancashire that year, he came close to adding a second career double-century to his name. However, he was dismissed on 197,
run out after collapsing with cramp. His run-scoring throughout 2006 earned him Kent's Player of the Year award. Walker was appointed
List A captain of Kent for the second half of the
2005 season, following the resignation of
David Fulton. However, he was unable to lead the team any higher than eighth in the second division of the
Pro40 League. In 2007, Walker hit the highest score of the innings in Kent's victory over
Gloucestershire in the
Twenty20 Cup Final. However, after finding first-team opportunities limited during 2008, he was released by Kent and signed for
Essex on a two-year contract. ==Coaching career==