Emma McKeon has locked in the world short course championships sprint double, adding the 50 metres freestyle to her 100m crown in Melbourne on Saturday night.

The 28-year-old got off to a flying start and led at the 25m turn before burning up the second lap for a clear win ahead of Poland's Katarzyna Wasick and Great Britain's Anna Hopkin.

McKeon's time of 23.04 seconds topped her previous personal best by 0.46 and set a championship record, while also bringing Australia's gold medal tally to 11.

Despite her dominance, McKeon said she did not consider herself a 50m swimmer.

"I still don't actually call myself a 50m freestyle specialist — I prefer the 100," she said.

"But I just knew that I had to kill that start and probably one of my strengths is my start so I knew if I got that I could be in contention."

McKeon, owner of 11 Olympic medals, had never won an individual world championship title at either short or long course before the Melbourne meet.

The victory came after she also helped the Australian women smash another relay world record, taking gold in the 4x50m medley earlier in the evening.