|Representing Great Britain|
|ITU Triathlon World Championships|
|ITU Duathlon World Championships|
|45-49F ITU World Triathlon Championship|
|2018 Gold Coast||Individual|
Dillon's first Olympic triathlon was at the 2000 Summer Olympics. She was one of the three British athletes, along with Sian Brice and Andrew Johns, not to finish the competition. Four years later, at the 2004 Summer Olympics, Dillon finished in sixth place with a time of 2:06:00.77.
Michelle has been a coach for many triathletes including Stuart Hayes and Emma Pallant. She returned to competitive sport on 3 April 2016 coming second in the British Duathlon Championships. In 2018 she became 45-49F World Triathlon Champion on the Gold Coast.