Australia has won the Olympic women's 4x100m freestyle relay gold medal at the Tokyo Games in a world-record time.

Flagbearer Cate Campbell, Emma McKeon, Meg Harris and Bronte Campbell torched their opposition to win Sunday's final in three minutes 29.69 seconds at the Tokyo Aquatics Centre.

The time bettered Australia's previous world benchmark of 3:30.05 set at the 2018 Commonwealth Games.

And the comprehensive victory - almost three seconds ahead of silver medallists Canada - delivers Australia a third consecutive Olympic title in the event.

Cate Campbell, who with basketballer Patty Mills carried Australia's flag at Friday night's opening ceremony in Tokyo, has featured in all three relay victories.

At the 2016 Rio Games, she teamed with her sister Bronte, McKeon and Brittany Elmslie to collect gold.

And four years prior in London, Australia's team of Cate Campbell, Elmslie, Alicia Coutts and Mel Schlanger also saluted.

In Sunday's final in Tokyo, the Australians were gifted early momentum by Bronte Campbell, who left her team lurking ominously in second spot after her leg.

Teen Harris then took the lead on the second leg and the Australians were never challenged thereafter, with McKeon and finally Campbell increasing their advantage.