O'Brien made her debut for Brisbane Roar on 18 October 2015 in a match against Canberra United.[3] She made twelve appearances for the team during the 2015–16 W-League season. Brisbane finished in fourth place during the regular season securing a berth to the playoffs.[3][4] During the semifinal match against regular season champions Melbourne City, the Roar was defeated 5–4 in a penalty kick shootout after 120 minutes of regular and overtime produced no goals for either side.[5]