Though born in London, Addison moved to Nottingham at the age of three,[2][3] where he was spotted by scouts from the Derby County youth system when he was playing for Clifton All Whites FC.

[4] Addison was handed his first team debut by interim manager Terry Westley, who he had worked closely with in the youth and reserve teams, towards the end of the 2005–06 season, in the 1–1 Championship draw with Hull City on 17 April 2006,[2] where he played in the centreback position alongside side another academy graduate Lewin Nyatanga.

With the appointment of Billy Davies as Derby manager, Addison found himself frozen out of the first team at Derby and didn't appear in the starting eleven again until Davies' successor, Paul Jewell, gave him a surprise start, again at centreback, in a 3–1 defeat away to Blackburn Rovers in the penultimate game of the 2007–08 Premier League season.

[7] Starting in his preferred position of central midfield for the first time, Addison impressed enough to retain his place for the subsequent match away to Barnsley.

[8] This was the start of a run of 15 consecutive appearances in the first team, which was only ended when suspension for reaching five yellow cards ruled him out of the League Cup 4th round tie against Leeds United.

[9] Addison formed a formidable midfield partnership with Paul Green during this time as the Rams embarked on a run of only two defeats in 13 matches and moved from the bottom of the table to the fringes of the playoff places.

Addison was substituted during Derby's 4–1 win over Blackpool, an injury which was later diagnosed to be a stress fracture of his foot, which ruled him out for the rest of the 2008–09 season.

[20][21] However, Addison made a quicker than expected recovery, with Clough suggesting he may be back in first team action as early as January 2011.

He was pencilled in to play a reserve game against Sheffield Wednesday on 26 October 2010,[22] but was later withdrawn as a precaution after admitting he felt "a bit stiff".

[23] He eventually took to the pitch in a competitive capacity when he came on as an 81st-minute substitute in a 2–0 home win over Portsmouth on 6 November 2010, his first appearance in 10 months, as Derby reached 4th in the table.

[33][34] After his loan spell finish at Barnsley, Addison found first-team appearances hard to come by at Pride Park due to the form of central defenders Shaun Barker and Jason Shackell.

[53] However, over the next two seasons at Bournemouth, Addison found his first team opportunities at the club hard to come by and appeared on the substitute bench.

[58] Although he was featured in the starting lineup in number of matches,[59] Addison was soon sidelined out of the first team, due to fallen out of favour and his own injury concern.

[63] However, he suffered an injury during a 2–1 win over Walsall on 30 August 2014 and his loan spell with the club was terminated shortly after, as he went on to make five appearances for the side.

[75] Addison made his Kilmarnock debut, where he started the whole game, in a 0–0 draw against Partick Thistle on 2 April 2016, keeping a clean sheet.

[78] He scored his first goal for the club on 22 May 2016 as Killie beat Falkirk 4–0 in the second leg of the Premiership play-off final at Rugby Park.

[83] Then, on 22 October 2016, Addison captained the side for the first time in four years, in a 1–1 draw against Inverness CT.[84] However, he suffered a foot injury that he sustained in late–November and was sidelined until late–January after surgery.

[88] Addison made his Nuneaton Borough debut, where he started the whole game, in a 0–0 draw against Ashton United, keeping a clean sheet in the process.

[93] Addison was called up to the England under-21 for the team's UEFA U21 European Championship Qualification games against FYR Macedonia and Greece on 27 August 2009.