Emily dominated at the 2015 FINA World Swimming Championships, winning gold in the 100-metre backstroke, 200-metre backstroke and the 4 x 100-metre freestyle relay. She broke the Commonwealth 200-metre backstroke record and became the first Australian to win the 100-metre/200-metre backstroke double at the world championships. At the 2015 Australian Short Course Championships she became only the second woman in the world to beat two minutes in the 200-metre backstroke, just 0.26 seconds outside the world record.