Career
Kelly began his career with Street Mirren and made his professional debut on 3 August 2013 in a 3–0 defeat against Inverness Caledonian Thistle. On 22 November 2013 it was announced that Kelly had signed a two-year contract extension with Saints, tying him to the club until the summer of 2016. On 5 March 2014, Kelly made his debut for the Scotland Under 21 side in a 2–2 draw against Hungary at Tannadice.
