Australia has voted "yes" to legalising same-sex marriage in a landmark national postal survey on the issue.

Crowds erupted in capital cities and towns across the nation as David Kalisch, the head of the Australian Bureau of Statistics, confirmed the "yes" vote had triumphed in the three-month campaign.

Kalisch announced on Wednesday morning that 7.8 million Australians (61.6% of eligible voters) supported legalising same-sex marriage in Australia, versus 4.8 million (38.4%) who voted "no".

All Australian states and territories recorded a majority "yes" vote, with the highest being the ACT at 74%, and the lowest being New South Wales at 57.8%.



A total of 133 of of 150 electorates had a majority "yes" vote. Participation in the survey was 79.5% or 12.7 million people.

In Sydney, a crowd of thousands danced, sobbed, and hugged their friends and family when Kalisch announced the result. Seconds later, "Love Is in the Air" started blasting out of the speakers.

Back in Parliament House, a group of MPs and senators watched the announcement on TV. Penny Wong, who has two children with her partner Sophie Allouache, buried her face in her hands, crying, seconds after the result came down. Tim Wilson also watched on with his partner, Ryan Bolger, who he has been engaged to for seven years.

Prime minister Malcolm Turnbull said it was time for the Parliament to do its job.

"Now it is up to us, here in the Parliament of Australia to get on with it, to get on with the job the Australian people have tasked us to do, and get this done. This year. Before Christmas," Turnbull said.

Finance minister Mathias Cormann said it would be up to the politicians in parliament to now work together to find common ground on a bill that will pass the parliament.

Opposition leader Bill Shorten declared it was a "fabulous day" to be an Australian because Australia is ready for marriage equality. He gave thanks to the LGBTIQ community.

"You shouldn't have had to put up with this survey but you embraced it. I feel for young people who have had their relationships questioned in a way in which I wouldn't have thought we would have seen ever again," he said.

"Unconditional love always has the last word."

The result does not automatically legalise same-sex marriage, but means the government will allow a vote on a private members' bill in the parliament – a crucial step towards legislation.

A bill is expected to be introduced to the Senate this afternoon, and then will track its way through the parliament – likely facing significant amendments from the right wing of the government.

Follow our live coverage of the postal survey result and reaction HERE.