Coker joined Bury Town in October 2008 from fellow Southern League side Barton Rovers. He was previously with Conference side Histon. He impressed on his debut for Bury, earning the sponsors man of the match award. Coker helped the Suffolk club win promotion to the Isthmian League. In summer 2010, Coker joined Colchester United after he impressed in a trial period at the end of 2009–10 season, having done well for non-league Bury Town during the 2009–10 campaign. On 30 September 2010, Coker joined Chelmsford City on loan for a month. The loan was extended by a further month and was given permission to play in an FA Cup tie against Hendon. On 14 January 2011, Coker made his debut for Colchester against Bournemouth in a 2–1 victory, providing assists for both goals. He was awarded the Colchester United Young Player of the Year award at the end of the 2010–11 season, his first with the club. On 15 May 2012, Coker signed a 12-month contract extension to see him through to summer 2013 with Colchester. On 12 October 2012, Coker was loaned to former club Histon on a month-long deal. On 4 February 2013, Coker had his contract with Colchester cancelled by mutual consent having made only two first-team appearances in the 2012–13 season. He returned to Histon permanently on 8 February 2013 following a loan spell earlier in the same season.
Prior to the 2013–14 season, he played in three friendlies for Southend United, impressing sufficiently in the games he played to be offered a contract by manager Phil Brown. On 16 April 2014, Coker signed a new two-year deal at Southend United, keeping him contracted until June 2016, and on 7 August 2015 this was extended for another 3 years with an option for a further year. On 27 October 2018 he suffered a serious knee injury whilst playing for Southend against Sunderland, and did not play any more games that season. His struggle to revoder from the injury was the subject of a BBC documentary series entitled 'Coming Back',. He never played any more games for Southend, and was released by them at the end of the 2018–19 season.
Lincoln City
On 23 August 2019 it was announced that he had signed for Lincoln City. He only played one cup game before being loaned to Cambridge United in January 2020.
