McKeown clocked a blistering time of 2:03.14s at the NSW State Open Championships at Sydney Olympic Park.

The previous leading world mark was 2:03.35s set by Regan Smith of the US at the 2019 World Championships.

The 21-year-old McKeown also holds the 100m backstroke world record.

She has three Olympic gold medals, all from the Tokyo Olympics in 2021, in the 100m and 200m backstroke and the 4x100m medley.

“After the Olympics I found it hard to get up behind the blocks again,” Australian media quoted McKeown as saying.

“(But) I’ve found a new love for the sport and it just goes to show that a happy swimmer is a fast swimmer.

“I haven’t necessarily changed anything in my programme or training-wise. It’s just that I’m happier.”

McKeown claimed gold in the 200m backstroke at last year’s World Championships in Budapest.

The World Championships this year are in Fukuoka, Japan, in July.