Downing started his career at Middlesbrough, where after a loan at Sunderland, he became a key part of the team, winning the League Cup in 2004 and helping them to the UEFA Cup final two years later. In 2009, after Boro's relegation, he joined Aston Villa for an initial £10 million, then moved on to Liverpool for twice that amount two years later, again winning the League Cup in 2012. He played for two seasons at West Ham United before returning to Middlesbrough, where he won promotion to the Premier League. In 2019, he was released by Middlesbrough after 404 total appearances, and signed for Blackburn Rovers.