At the 2012 Summer Olympics, Elmslie represented the gold medal-winning Australia team (with Cate Campbell, Alicia Coutts and Melanie Schlanger in the final) of the 4 × 100 metre freestyle relay, where the team set a then-Olympic Record of 3:33.15. Elmslie also won two silvers, as part of the Australian teams in the competitive heats of both the 4 × 100 metre medley relay and the 4 × 200 metre freestyle relay.