At the 2000 Olympics in Sydney Rooney won two silver medals as a part of the 4×200-metre freestyle relay (with Kirsten Thomson, Susie O'Neill and Petria Thomas) and 4×100-metre medley relay (swum in morning preliminary session).
In 2001 Rooney claimed the world champion title in the 200 m freestyle, winning at the 2001 Fukuoka World Swimming Championships in Japan.