Fahey made his Birmingham debut on 17 January 2009, coming on as a late substitute in a 1–1 draw against Cardiff City. He scored his first goal for the club, a "delicate lob" which the player admitted was meant to be a cross, to clinch a 2–0 home victory against Nottingham Forest on 14 February. His second goal gave the Blues a 1–0 home win over Southampton some weeks later. Fahey retained his place in the side for the rest of the season (keeping loan signings Scott Sinclair and Hameur Bouazza out of the starting eleven), and was a key player for Birmingham in their successful bid for promotion to the Premier League, scoring a goal and making a goal in a vital 2–1 win at Reading on the last day of the campaign.