Harris, the Paris Olympics silver medallist, powered home in 24.02s to beat Chinese pair Wu Qingfeng (24.26s) and Cheng Yujie (24.28s).

The American Walsh, who won gold in the 50m and 100m butterfly in Singapore, finished fourth in 24.40s.

Australia also won the men’s 50m freestyle, with Cam McEvoy taking gold yesterday.

Harris said becoming an individual world champion was “the dream I have been dreaming of the whole time”.

“This is why I swim,” said the 23-year-old, who could not stop smiling as the magnitude of her achievement set in.

“I still can’t put it into words, it’ll take a while to process.”

World record holder Sarah Sjoestroem of Sweden, the reigning Olympic champion and a four-time world title-holder in the event, did not compete in Singapore.

“I love sprinting, I love racing. Could not be more happy,” added Harris.

The Australian has now won six world golds in her career.

The previous five were in relay events.