Cairns began his career in the Leeds United youth academy and turned professional with the club at the end of the 2010–11 season. Cairns joined Celtic on a month-long loan after first-choice goalkeeper Andy Ralph suffered a suspected broken leg in the Badgers' opening game of the season. He made his debut for the club at their home ground in a 1–1 draw against Gainsborough Trinity and kept his first clean sheet later that week in a 0–0 stalemate against Droylsden. At Stalybridge Celtic's end of season awards on 27 April 2013, Cairns won the Player of the Year, Players' Player of the Year and Supporters' Player of the Year awards. Cairns was recalled to Leeds on 26 April 2013. In May 2014, Cairns extended his contract with Leeds by a further year. In July 2015, Cairns signed a six-month contract at Chesterfield, and later signed with Rotherham United until the end of the season. The move reunited him with Rotherham manager Neil Redfearn, who had previously been his academy manager at Leeds United. In July 2016, Cairns signed for Fleetwood Town, where he went on to establish himself in the first team. He played a total of 81 games in his first two seasons at the club, keeping 34 clean sheets. On 26 November 2022, Cairns joined Hartlepool United on a seven-day emergency loan deal. In January 2023, Cairns joined League Two side Salford City on loan for the remainder of the 2022–23 season.