He missed a number of matches for Queens Park Rangers due to a posterior cruciate ligament injury which at one stage led doctors to believe that his career was over.

Carlisle was named man of the match for his performance in the play-off final as Burnley beat Sheffield United 1–0 to return to the top tier of English football for the first time in 33 years.

He attended Balshaw's Church of England High School where he attained 10 A-grades at GCSE and studied mathematics and politics at A-level[citation needed], and in 2002 was awarded the title of "Britain's Brainiest Footballer" in a TV game show.

[3][4] He went on to study A-level mathematics and politics at Ealing, Hammersmith and West London College while he was unable to play football due to an injury.

[5] Carlisle has a degree in Professional Sports Writing and Broadcasting from Staffordshire University,[6] and has expressed interest in taking up teaching work following his football career.

[8] He scored his first goal as a professional footballer with the 90th-minute winner in the following match, a 2–1 win against Carlisle United at Blackpool's home ground, Bloomfield Road.

[11] Despite the team's relegation, Carlisle's strong defensive performances during his three years at Blackpool attracted the attention of Iain Dowie, who at the time was a scout for Queens Park Rangers.

After missing the entire 2001–02 campaign, Carlisle returned to competitive football on 7 September 2002 in Queens Park Rangers' 4–0 victory over Mansfield Town.

He subsequently missed one month of the season after being admitted to Sporting Chance, a clinic run by former England international footballer Tony Adams, for 28 days for treatment for alcohol-related problems.

Watford manager Aidy Boothroyd, who had been a coach at Leeds during the previous season, was pleased with the signing, stating that Carlisle was "exactly the type of defender I wanted".

[30] Carlisle was placed straight into Watford's starting line-up and played his first match for his new club on 6 August 2005, but he could not prevent the team losing 2–1 to Preston North End at Vicarage Road.

[33][34] Soon after, Carlisle scored two goals in a competitive match for the first time in his career, grabbing both in Watford's 2–1 win against Wolverhampton Wanderers in the second round of the League Cup.

[33] On 4 November 2005, Wolverhampton Wanderers manager Glenn Hoddle accused Carlisle of stamping on goalkeeper Michael Oakes in the match the previous weekend, and threatened to report him to the Football Association.

[37] The thigh problem caused him to be unavailable for the play-offs as Watford defeated Leeds 3–0 at the Millennium Stadium to win promotion to the FA Premier League.

[40] On 2 March 2007, Carlisle joined local rivals Luton Town on a one-month emergency loan deal in an attempt to return to full match fitness.

[41] He made his debut for Luton the following day in the 3–2 away defeat to Wolverhampton Wanderers in the Championship, coming on as a substitute for Matthew Spring, who had himself joined the club from Watford earlier in the season after failing to break into the first team.

[42] Carlisle went on to play in Watford's following three league matches of the season as their relegation back to the Championship was confirmed after a 1–1 draw with Manchester City at Vicarage Road.

[42][45] On 14 August 2007, Steve Cotterill, manager of fellow Championship club Burnley, made an offer of £200,000 for Carlisle, who signed a three-year contract at Turf Moor two days later.

[49] Carlisle scored his first goal for Burnley on 22 September 2007, netting a stoppage time minute equaliser with an overhead kick in the 2–2 draw with Bristol City at Ashton Gate.

[53] Carlisle was handed the man of the match award for his performance as Burnley triumphed 1–0 against Sheffield United to earn promotion to the Premier League for the 2009–10 season.

[55][57] He also played in the following match as Burnley recorded their first ever Premier League victory, a 1–0 win over reigning champions Manchester United at Turf Moor.

[62] After serving a three-match suspension in October 2010 following a red card in the 1–1 draw away at Millwall,[63] Carlisle returned to the team for the League Cup tie against Aston Villa and scored an 89th-minute equaliser to take the match to extra time.

[64] He made 41 appearances during the campaign but was not deemed a first-choice player by new manager Eddie Howe, and in July 2011 he joined his hometown club Preston North End on loan for the duration of the 2011–12 season.

[68] Preston manager Phil Brown brought in Jamie McCombe on loan as cover for Carlisle, and the Huddersfield Town loanee kept his place in the starting line-up throughout December 2011.

Carlisle returned to the Preston team for the visit to Rochdale on 2 January 2012, when he was selected to play alongside Craig Morgan by caretaker managers Graham Alexander and David Unsworth.

[66] Following the appointment of Graham Westley as Preston manager, Carlisle struggled to fit the new training regime in with his commitments as chairman of the Professional Footballers' Association and his loan deal was cancelled by mutual consent on 31 January 2012.

[69] Later the same day, Carlisle signed for League Two club Northampton Town, managed by former Watford boss Aidy Boothroyd, on loan for the remainder of the season.

He was called up to the squad by Howard Wilkinson, and made his debut for his country on 31 August 2000, coming on as a substitute in England's 6–1 friendly victory over Georgia at the Riverside Stadium in Middlesbrough.

[88] In February 2012, he was part of a PFA delegation that met with British prime minister David Cameron to discuss the issues of racism and homophobia in the sport.

[101] On the morning of 22 December 2014, Carlisle was hit by a lorry on the A64 near Bishopthorpe, North Yorkshire, and was airlifted to Leeds General Infirmary[102] having suffered cuts, bruises, internal bleeding, a broken rib and a shattered left knee.