He joined Sunderland in January 2008 for an initial fee of £850,000. Bardsley established himself as a regular at the Stadium of Light under Steve Bruce and Martin O'Neill and he won the player of the year award in 2010–11. He lost his place in the team in 2012–13 after a falling-out with manager Paolo Di Canio, before returning to the first team under Gus Poyet. Under Poyet, Bardsley helped Sunderland to avoid relegation in 2013–14 and reach the 2014 Football League Cup Final, in which they lost 3–1 to Manchester City.