The women's 300 metre freestyle was a swimming event held as part of the swimming at the 1920 Summer Olympics programme.

[1] It was the first appearance of the event, which was later adjusted to 400 metres to match the men's competition.

A total of 16 swimmers from seven nations competed in the event, which was held on Thursday, August 26 and on Saturday, August 28, 1920.

In the first semi-final Ethelda Bleibtrey set a new world record with 4:41.4 minutes.

She bettered her own record in the final with 4:34.0 minutes.