 Byrne joined Arsenal in January 2000 and quickly became their first choice goalkeeper.She won a domestic treble in her first full season with Arsenal, saving a penalty in the 2001 FA Women's Cup final win over Fulham, and was voted club Players' Player of the Year in 2003 and 2005.She became a European champion with Arsenal in April 2007, when they beat Umeå IK in the 2007 UEFA Women's Cup Final 1–0 on aggregate, a tie in which she made numerous vital saves in the home and away games.