At the 2016 Summer Olympics, Elmslie represented the gold medal-winning Australia team (with sisters Cate Campbell and Bronte Campbell and Emma McKeon in the final, along with Madison Wilson in the heats) of the 4 × 100 metre freestyle relay. In the final of the event, the Australian team set a then 4 × 100 metres freestyle relay World Record time of 3:30.65. Elmslie also won silver as part of the Australian team in the competitive heats of the 4 × 100 metre medley relay.