At the 1996 Summer Olympics in Atlanta, Mackie swam in the heats of the 4×200-metre freestyle relay, before being replaced in the finals as Susie O'Neill, Nicole Stevenson, Emma Johnson and Julia Greville trailed the United States and Germany, to claim bronze.
At the 1996 Summer Olympics in Atlanta, Mackie competed in the heats of the 4×200-meter freestyle relay before being replaced in the finals as Susie O'Neill, Nicole Stevenson, Emma Johnson and Julia Greville trailed the United States and Germany to secure bronze.