Williams' club career started with Chelsea then she progressed to Charlton Athletic in 2001. She signed for Everton in 2004 and later captained the club, winning the Premier League Cup in 2008 and the FA Women's Cup in 2010. After eight years with Everton she signed for local rivals Liverpool in 2012 and won the league title in 2013 and 2014. Williams was named The Football Association (FA) Young Player of the Year in 2002, FA Players' Player of the Year in 2009 and FA International Player of the Year in both 2007 and 2009.