On 24 June 2013, McCormack signed a two-year contract with Brentford, who had remained in League One after suffering defeat in the 2013 League One play-off final. He began the 2013–14 season in his natural midfield position, before being moved to right-back by manager Uwe Rösler in October, to replace out-of-form Shay Logan.
In June of 2013, McCormack signed a two-year contract with Brentford after they finished the 2013 League One season without winning the play-off final. He began the 2013–14 season in his usual midfield position but was moved to right-back by manager Uwe Rösler in October to replace Shay Logan, who wasn't performing well.