She represented Australia at the 2012 and 2016 Summer Olympics in swimming, and won a gold medal in the 4 × 100 m freestyle relay at both Games.

[3] As of 2012[update], she lives in Brisbane,[4] having moved there from Noosa (where she attended Good Shepherd Lutheran College) in 2011 in order to improve her chances of making the Olympics.

[7][8] Elmslie initially studied Business at Griffith University, majoring in Events and Sports Management.

[8] In 2011, after moving to Brisbane to join other swimmers coached by Matt Brown, Elmslie increased her training regime and lost 6 kilograms (13 lb).

[18] In the final sisters Cate and Bronte Campbell, Emma McKeon and Alicia Coutts won the silver medal, finishing 0.12 of a second behind the United States team.

In the final of the event, the Australian team set a then 4 × 100 metres freestyle relay World Record time of 3:30.65.

[20] Elmslie also won silver as part of the Australian team in the competitive heats of the 4 × 100 metre medley relay.