Career
Gallagher came through the Rangers youth system. He played for Alloa Athletic and East Stirlingshire on loan to gain first team experience whilst a youth team player with Rangers. On 15 March 2014, Gallagher made his Rangers debut and scored in a 2–0 victory over Dunfermline Athletic.
He joined Cowdenbeath on loan in September 2014.
Gallagher left Rangers in August 2015 and signed a one-year contract with Street Mirren. Gallagher scored his first goal for Street Mirren in a 3–2 defeat against Livingston in the Scottish League Cup on 25 August 2015.