Melissa Breen narrowly missed the 100m Olympic A qualifying mark by an agonising 0.01s when she ran 11.30 seconds in Japan in March 2012. She was rewarded for her consistent efforts however with Olympic nomination based on selector's discretion. The Canberran went on to make her Olympic debut at the London 2012 Games where she finished sixth in the 100m heat in a time of 11.34 seconds, narrowly missing out on the semi-finals.
Breen cut it close again in qualification for Rio, finally posting a qualifying time in June, 2016. At the Games, she again exited in the heats, finishing seventh with a time of 11.74.