At the 2008 Summer Olympics, Parker represented Great Britain in the 3000 metres steeplechase. She was eliminated in the heats, running 9:51.93. She reached the final of the 3000 m steeplechase at the 2011 World Championships in Daegu after running 9:38.12 in her heat. In the final, she finished 14th with 9:56.66.
In June 2012, Parker broke the UK record in the 3000 m steeplechase with 9:24.24, which was unsurpassed until 2021. She competed at the London 2012 Olympic Games and was eliminated in the heats of both the 3000 m steeplechase and 5000 metres. In the 3000 m steeplechase, she ran 9:32.07, while in the 5000 m, she ran a personal best of 15.12.81.