Born in Chesterfield, Derbyshire, King started his career at Leicester City where he came through their youth academy alongside Joe Mattock, Max Gradel, Andy King (unrelated), and Luke O'Neill, he signed a two-year pro-contract on 2 September 2008.
[2] King made a match squad for the 1st time in Leicester's 3–0 Football League Trophy victory over Hartlepool United, however he was an unused substitute on that occasion.
[3] However, he did make his debut the following round as a half time substitute replacing Steve Howard against Lincoln City.
[4] On 17 September 2009, King joined Hereford United on a one-month loan, and scored within six minutes of his debut in a 2–0 win over Accrington Stanley.
On 18 May 2009 King was called up to the Scotland under-19 squad for the UEFA European Championships Elite round, to be held at Bramall Lane, Sheffield.