Former Australian prime minister Julia Gillard has endorsed US presidential candidate Hillary Clinton in a new video released overnight.

Ms Gillard worked closely with Ms Clinton when the pair were prime minister and secretary of state, respectively, including on strategic initiatives such as America's so-called "pivot" to the Asia Pacific and the decision to rotate a small force of marines through Darwin.

And Ms Gillard, who has herself become something of a feminist icon for her famous misogyny speech, joins a host of American diplomatic heavyweights in praising Mrs Clinton's time as secretary of state in the Obama administration.

"Hillary Clinton understood in her heart how important it was for girls to get an opportunity but she also understood in her head that if we want to build peaceful, economically prosperous nations, then we have to educate girls," Ms Gillard says in the video.