She was the gold medallist at the 2011 and 2012 European Cross Country Championships.
She has represented Ireland in the steeplechase at the 2008 Beijing Olympics and 2012 London Olympics, the 2007 World Championships in Athletics and 2011 World Championships in Athletics, and twice at the European Athletics Championships.
In December 2012, Britton became the first woman to successfully defend the European Cross Country Championship.