Gallagher joined the Chicago White Sox as a non-roster Spring training invitee in , but again failed to make the major league roster, and was reassigned to triple A. He batted .336 with four home runs in 34 games with the Vancouver Canadians to earn a call up to the majors on May 13. In his first game for the Chisox, Gallagher went two for three with a triple, a walk two RBIs and two runs scored to lead his team to a 7–5 victory over the Toronto Blue Jays. The following day, he hit a home run off Mark Eichhorn in the thirteenth inning for the walk off victory over Toronto.