Walters started his senior career at Blackburn Rovers but failed to break into the first team and joined Bolton Wanderers.

He then went on to play for Wrexham and Chester City before finally finding regular football at Championship side Ipswich Town.

Walters remained a regular at Stoke under managers Tony Pulis and Mark Hughes, scoring 62 goals in 271 appearances, before joining Burnley in July 2017.

He played in four Premier League games for Bolton making his professional debut as an 85th-minute substitute in a 2–1 defeat to Charlton Athletic, before signing for Hull City on loan in 2003.

[23] Walters agreed terms with Ipswich on a deal worth £100,000 plus add-ons in mid-January 2007, having impressed in FA Cup ties between the clubs earlier in the month.

[27] He scored his first ever senior hat-trick in the 6–0 win over Bristol City in November 2007 at Portman Road,[28][29] in the same week he received a call-up to the Republic of Ireland B squad.

[31] He had surgery on a niggling knee problem on 19 March 2008 and returned to action against Norwich City on 13 April in half the expected time.

Walters played 41 times for Ipswich scoring 13 goals in 2007–08 as the Tractor Boys missed out on a play-off place by just one point.

[35] In August 2010, Walters expressed to Roy Keane his desire to leave Portman Road after Stoke City made an offer for him.

[36] On 18 August 2010, Walters joined Premier League side Stoke City for an initial £2.75 million fee on a four-year contract.

[43] In November, Walters scored twice for Stoke in a 3–0 win over West Bromwich Albion, the first goal coming from the penalty spot and the other via a rebound from Scott Carson.

[62] On his 100th appearance for Stoke, Walters scored twice against his old club Bolton Wanderers in a 2–2 draw on the final day of the season, a result which relegated the "Trotters".

[63] Walters continued to be a virtual ever-present in the 2012–13 season as he went on to make a club-record 61 consecutive Premier League starts by 3 November 2012.

[64] He scored a well-worked set-piece in a 1–1 draw against West Ham United which earned praise from pundit Gary Neville.

[66] On 12 January 2013, whilst playing against Chelsea, Walters scored two own goals becoming only the fourth player to do so in the Premier League, he also missed a penalty in the match as Stoke lost 4–0.

[71] On 10 November 2013, Walters featured in his 100th consecutive Premier League match and marked the occasion by scoring in a 3–3 draw with Swansea City.

[83] With Walters entering into the final year of his contract, Stoke rejected a bid from Norwich City at the start of the 2015–16 season.

[92][93] On 7 July 2017, Walters joined fellow Premier League side Burnley on a two-year contract for a fee of £3 million.

[94][95] He was restricted to just five appearances in the 2017–18 season as he struggled with a recurring knee injury and on his return to action wasn't able to force his way into Sean Dyche's plans.

[101] He was called up in November 2010 for the friendly match against Norway[102] and was brought on as a half-time substitute in that game to make his senior international début.

[104] On 26 March 2013, Walters scored two goals against Austria before a late strike from David Alaba gave the Austrians a 2–2 draw.

[105][106] In May 2021, Walters was invited to join the coaching staff of Republic of Ireland U19s for a three-day training camp based in England.

[109] On 22 February 2024, following the departure of Ricky Martin, Walters returned to former club Stoke City in the role of Interim Technical Director.