Some 61.6% of voters supported the move in a postal vote
Australians have voted to legalise same-sex marriage by an overwhelming margin in a national survey.
Some 61.6% of voters supported Australia becoming the 26th nation to legalise same-sex marriage, after countries such as Ireland, the US, Canada, New Zealand and the UK.
There were 38.4% opposed to the move.
The Equality Campaign said a greater percentage of people participated in this vote than in Brexit, the British general election, the Irish marriage equality referendum and the the US presidential election.
Here, Children's Minister Katherine Zappone said: "The Yes result shows that when given a chance people across our world will speak out and demand equality for all.
"The outcome will boost marriage equality campaigners in Northern Ireland and elsewhere.
"It will also send a message of solidarity to those who cannot express their love because of threats of discrimination, prosecution and even violence.
"All who campaigned in Australia are to be congratulated. This is their moment, as it was ours in May 2015.
"However we should also remember that equality is hard fought, precious and fragile. It must never be taken for granted.
"Despite the huge steps forward of recent years it is a sad reality that one-in-five young LGBTI+ people in Ireland continue to report discrimination and bullying.
"Next month I will give an important update on our LGBTI+ National Youth Policy - it is a world first. I will also during a visit to Belfast stand in solidarity with campaigners fighting for marriage equality there.
"For now I offer my congratulations to Australian voters worldwide who have spoken out in their millions and demanded change."
One of those who voted "Yes" was Hamish Koci (37) from Melbourne, who said he felt "a bit delirious" following the result.
He said: "I'm actually lying in bed right now exhausted because I couldn't sleep last night, I guess in anticipation of the result today.
"I'd cleared my schedule for today, thinking I'd want to be at my local gay bar, surrounded by friends.
"But it turned out I needed to be alone for whatever result was announced, because my emotional reaction was going to be extreme either way, and I didn't think I could do that in the glare of even a supportive crowd.
"I will join them later.
"So my reaction has been weepy, and happy, but still angry, and quite drained. It really was an unnecessarily long and taxing process, and it's not even over yet.
Almost 80% of eligible voters - 12.7 million people - participated in the voluntary postal survey.
At a gathering after the result in Sydney MP Alex Greenwich, co-chair of the Equality Campaign, said: "Love has had a landslide victory."
In comments reported by the Sydney Morning Herald, he told the thousands in the audience: "Getting to this point has not been easy, but rarely in your life can you celebrate with such pride overcoming adversity to make history."
Each of Australia's states and territories voted 'Yes' by more than 60%, except for New South Wales (57.8%).
The ACT (Australian Capital Territory) had the highest 'Yes' vote (74%), followed by the state of Victoria (64.9%).
Australia's Prime Minister Malcolm Turnbull said on Twitter: "The people of Australia have spoken and I intend to make their wish the law of the land by Christmas.
"This is an overwhelming call for marriage equality."
The people of Australia have spoken and I intend to make their wish the law of the land by Christmas. This is an overwhelming call for marriage equality. pic.twitter.com/PWZbH5H71r— Malcolm Turnbull (@TurnbullMalcolm) November 14, 2017
The poll is non-binding but the government there had promised to allow parliament to consider a bill to create marriage equality in Australia during its final two-week session, which is due to end on December 7th.
This means that a law allowing same-sex marriage could be a reality by Christmas.
A recent poll by the Australian Broadcasting Corporation (ABC) found that 72% of the lower House of Representatives would support changes to marriage laws and in the Senate, 69% would approve the changes.
Praise of the vote has been flooding in:
Love wins in Australia! Thrilled to hear Australians have voted in favour of legalizing same-sex marriage. #MarriageEquality— Justin Trudeau (@JustinTrudeau) November 15, 2017
Wooohoooo marriage equality in Australia ! ?? pic.twitter.com/JRTt9qFpvE— ADAM LAMBERT (@adamlambert) November 15, 2017
The Empire State Building lit up to show support for Australia’s marriage equality. pic.twitter.com/GhDGTpeiSy— Ahron Young (@AhronYoung) November 15, 2017
The Equality Campaign in Australia was headed by Irish man Tiernan Brady, who was also instrumental in passing Ireland's marriage equality referendum back in 2015.
YES!!! 61.6% pic.twitter.com/vv0yxCYNee— Tiernan Brady (@Tiernanbrady) November 14, 2017
Praise was also offered for Mr Brady by drag queen Panti Bliss:
I think Australia should give @Tiernanbrady honorary citizenship, make him a Dame, and give him a kangaroo or a billabong or whatever. He did an amazing job as Director of @AMEquality. He’ll probably never come home now though. #MarriageEquality— Dr Panti Bliss (@PantiBliss) November 14, 2017
?? THANK YOU ??— AU Marriage Equality (@AMEquality) November 14, 2017
This all happened because of you.
We did this together. pic.twitter.com/4vWuIj9bpB
Additional reporting: IRN