Williams joined Leicester City Women as a twelve-year-old, progressing through their centre of excellence to play in their senior side.

[6] The following season she was part of the Leicester team that won promotion to the FA Women's Premier League Northern Division.

[8] In October 2009 she scored against former club Leicester City Women as Doncaster progressed in the Premier League Cup.

[11] After converting to a striker, Williams made an impressive start to the new season with Birmingham, scoring five goals in her first two WSL appearances[12] and winning a recall to the England squad.

[14] She scored an injury time equaliser against Chelsea Ladies in the 2012 FA Women's Cup Final, which Birmingham eventually won after a penalty shootout.

[19] In July 2022, Williams signed a two-year contract with Manchester United, reuniting with her former Birmingham manager Marc Skinner.

[22] Her debut for the England senior side came in July 2009 when she came on as a substitute for Alex Scott in the 2–0 defeat at home to Iceland.

Williams was allotted 171 when the FA announced their legacy numbers scheme to honour the 50th anniversary of England's inaugural international.