Mears came through the ranks at Manchester City and signed trainee forms in August 2001. Mears only made one appearance for City, replacing Stuart Pearce as a substitute in the 84th minute against Nottingham Forest in March 2002. On Manchester City's promotion to the FA Premier League in 2002, Mears' first-team opportunities became limited and he was sold to Preston North End.
Mears joined Preston in July 2002, for a fee of £200,000. He signed a three-year contract and was expected to provide cover for Graham Alexander. He made his debut for Preston as a substitute in a 3–3 draw with Walsall in October 2002, and went on to make a total of 24 league and cup appearances in the 2002–03 season, as Preston finished in mid-table of the Football League Championship. He made only 14 appearances in the 2003–04 season and five in the 2004–05 season as a stress fracture put him out of the game for ten months. Despite his long-term injury, he was offered and signed a further three-year contract in March 2005, saying "I was out for 10 months so you worry about what is going to happen to you. You need to be in the team but Preston have been very good to me and I can't speak more highly of the manager. Last season to get the stress fracture was very hard but that's all behind me now and I'm looking forward to a fresh start with a three-year deal." He made 39 league and cup appearances in the 2005–06 season as Preston reached the Championship play-offs semi-final. During that season, instead of having his surname Mears on the back of his shirt, he had his nickname "Tye", a rare occurrence in English football. In July 2006, after rejecting two bids from Charlton Athletic, Preston accepted an offer for Mears from West Ham United.
Mears signed for West Ham for an initial £1 million in July 2006, rising to £1.9 million depending on appearances and possible future international recognition with England. However, he was only to make six league and cup appearances for West Ham as he struggled to break into the first team. He memorably produced an athletic overhead clearance on the line, after Stiliyan Petrov lobbed West Ham keeper Roy Carroll in a match against Aston Villa in September 2006.
With his opportunities in the West Ham first-team limited, he was allowed to join Derby County on loan until the end of the 2006–07 season in January 2007. Derby manager, Billy Davies, who had managed Mears at his previous club Preston, said of him, ""He is a very attacking full-back with excellent pace who adds great competition. Ideally we would like to make this deal permanent in the summer." He made his debut as an 84th minute substitute in a 1–0 win at Southampton on 3 February, and went on to make a total of 17 league and cup appearances, as Derby were promoted to the Premier League after beating West Bromwich Albion in the Championship play-off final in May. Mears then joined Derby permanently for £1 million in July 2007, signing a three-year contract. Manager Billy Davies said, ""We're delighted with this deal. Tye is a very good young full back with excellent pace and potential. We need him for the challenge ahead and I know he is committed to working hard." A stress fracture sustained in January 2008 ruled him out for three months of the 2007–08 season. Mears scored his first goal for Derby against Leeds United in a 2–0 win on the last day of the 2006–07 season. Mears scored his second goal for Derby in April 2008 against his former club West Ham.
On 29th August 2008, Mears caused controversy when he flew to France to go on trial with Olympique de Marseille without the express permission of Derby manager Paul Jewell. Jewell responded, saying that Mears would never play for the club again whilst he was in charge, and the club fined Mears six weeks wages. Following the trial, the clubs agreed that Mears would go on loan to Marseille for the duration of the 2008–09 season, for a loan fee of £160,000, with the French club having the option to buy him for £1.5m at the end of the loan. A combination of injury and the good form of Laurent Bonnart meant that Mears did not make his first appearance for Marseille until the UEFA Cup tie against FC Twente in mid-January. Following an injury in March that ruled Bonnart out for the rest of the season, Mears filled in at right full-back in his absence. He made his league debut against Paris Saint-Germain. His first goal for Marseille came in the second leg of a UEFA Cup knockout-stage match against Ajax. His goal, scored in the 20th minute of extra time, gave Marseille a 4–3 win on aggregate, allowing the team to progress to the competition's quarter-final round. Mears went on to make seven appearances in all competitions. Marseille decided not to take up the option of signing him at the end of his loan spell and he returned to Derby on 3 June 2009, with his future at the club in doubt.
On 26th June 2009, he was the subject of an accepted £500,000 (rising to £600,000 with add-ons) bid from Premier League side Burnley. He completed the move, signing a three-year deal on 30 June. Mears made his Burnley debut in a 2–0 defeat at Stoke City. He played in all 38 games as Burnley were relegated after finishing 18th in the 2009–10 Premier League and accumulated just 30 points. Following relegation, Mears began looking for a move away from Turf Moor due to his desire to remain in the top flight.
He scored his first goal for Burnley in a 2–1 win over his former club Derby County on 27th November 2010.
On 29 July 2011, Mears, along with Burnley teammate Chris Eagles, joined Bolton Wanderers on a three-year contract for a joint fee in the region of £3 million. However, on 4th August he broke his leg in a training session. Manager Owen Coyle later said he expected Mears to be absent for a minimum of five months. On 24th January 2012, Mears played his first full ninety minutes since his injury in the Reserve team's 1–0 defeat to Sunderland Reserves, he was an unused substitute in Bolton's 2–1 FA Cup win over Swansea City on 28th January. He made his full debut for the club when being named in the starting line up for the game at Norwich City on 4th February, which Bolton eventually lost 2–0. However, following the game Mears complained about a pain in the leg that had been broken the previous August and, after a screw was removed from the leg, manager Owen Coyle said he expected Mears to be out of action until late March. Mears didn't make another appearance for the rest of the season.
At the end of the 2013-14 season he was released by the club along with Chris Eagles, Zat Knight and Jay Lynch.
Though English by birth, Mears believed he had Jamaican ancestry and it was reported on 4th February 2009, that he had accepted an offer to play for the Jamaica national football team. Mears made his debut on 11th February 2009 against Nigeria, playing 71 minutes of the 0–0 draw at the New Den. Mears said, "It was a fantastic feeling to be selected. When John Barnes first phoned me I was really excited. It's a fantastic opportunity to play for Jamaica." Despite making an appearance for Jamaica, it was later revealed that Mears' father, whom he thought he qualified through, was actually from Sierra Leone.
His international career sums it all up really - didn't even now who is father was!
Another top drawer signing from Coyle, I don't know how he kept doing it?
Thank you, Owen.