Kelly trialled at Kilmarnock of the Scottish Premier League in July 2007, while Gretna were also interested in signing him, but refused to pay the £50,000 Derry wanted for him. Inverness Caledonian Thistle and Dundee United had also made inquiries about signing Kelly, although Inverness were only interested in loan terms. Kelly instead signed for Conference Premier side York City on a two-year contract on 29 August for an undisclosed five-figure fee, with family reasons being his motivation for moving to a British club. A day after signing for the club, he made his debut against Rushden & Diamonds and scored a late own goal, meaning his new side lost 3–2. He was ruled out for at least a month with a suspected torn hamstring in January 2008, which was picked up in training, and returned to the side in their 2–0 defeat against Cambridge United on 1 March 2008, after coming on as a 53rd-minute substitute for Darren Craddock. He finished the 2007–08 season with 33 appearances and two goals for York. Kelly drew praise from York manager Colin Walker following York's 2–0 victory against Woking in October, which was his first start of the 2008–09 season. Following this, he admitted fears over his future at York after struggling to feature in the team, having only made two starts since April. It was confirmed in March 2009 that he would leave York at the end of the 2008–09 season.