Purkiss joined Walsall in August of the same year and spent three seasons with the club, appearing on the losing team in the 2015 Football League Trophy final.

[15] Purkiss joined Conference National club York City on loan until the end of 2006–07 on 22 March 2007 in time for their play-off push.

[5] Purkiss had been considering a move to the club for some time and eventually agreed a deal that included a loan period and a four-figure sum for Gainsborough despite only five weeks being remaining on his contract.

[38] Purkiss left Oxford on 24 January 2012 after being released from his contract and subsequently signed for League Two rivals Hereford United.

[43] He missed the start of 2014–15 with an ankle injury but returned to first-team action with good energy after working hard to maintain his fitness levels.

[44] He was named on the Football League team of the week for his performance in a 2–0 win at Doncaster Rovers on 7 February, having denied the home side an equaliser with a goal-line clearance.

[45] He made a third losing appearance at Wembley Stadium on 22 March, as Walsall lost 2–0 to Bristol City in the final of the Football League Trophy.

[50] Manager Rob Page signed him as a replacement for departing right-back Frédéric Veseli to provide competition to Adam Yates.

[51] He began 2015–16 as the club's first choice right-back, combining well with winger Byron Moore, and impressed in the role to the extent that Yates was sent out on loan.

[52] Page praised Purkiss for his performances early in the season, and said his signing allowed the club to play a more patient, passing game.

[53] He was named in The Football League Paper team of the day for his performance in a 1–1 draw with Scunthorpe United at Vale Park on 12 December.

[63] On 28 June 2017, Purkiss signed for newly relegated League Two club Swindon Town on a free transfer, after turning down a new contract with Vale.

[64] On the opening day of the 2017–18 campaign, he made his Swindon debut during their 2–1 away victory against Carlisle United, featuring for the entire 90 minutes.

[70] Manager Dean Keates said that "he's made over 400 senior appearances and is chairman of the PFA, so he's an asset with a great affinity to the club".

[77] Purkiss plays as a right-back and speaking in 2010 Oxford manager Chris Wilder described him as "an athletic footballer who likes to get forward and join in".

[78] Purkiss was elected as chairman of the Professional Footballers' Association (PFA) in November 2017, succeeding Ritchie Humphreys after five years on the management committee.

[79] He called for an independent review into the PFA and criticized numerous decisions made by the leadership, including a perceived lack of support and research into mental health issues and dementia.

[83] John Mousinho was elected as chairman of the newly formed Professional Footballers' Association (PFA) players' board in May 2021.