All that needs to be changed to make same-sex marriage legal is a tweak to the Australian Marriage Act, which defines marriage as between a man and a woman.
Prime Minister Malcolm Turnbull says that could happen by Christmas but conservative politicians are pushing hard for extensive religious protections in any bill legalizing marriage equality, to shield "no" supporters and Christians, which could stall the bill's progress.
"Protecting fundamental freedoms -- freedoms such as parental rights, freedom of speech, freedom of religion and conscientious objection will be vital to alleviate the valid concerns of millions of Australians," vocal same-sex marriage opponent Liberal Party Senator Eric Abetz said in a statement after the result.
In total, 61.6% of Australians voted in favor of changing the definition of marriage to include same-sex couples, according to results announced Wednesday
, while 38.4% voted against.
More than 12 million people cast their votes, a turnout of 79.5%, and the "yes" vote won a majority in every state and territory, according to the Australian Bureau of Statistics.
"They voted yes for love, and 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," Turnbull said Wednesday morning.
Australia has long lagged behind the rest of the world on marriage equality, which has already been passed into law in most English-speaking countries.
Pointing to years of strong polling in favor of same-sex marriage, opposition parties had argued for Parliament to legislate without a postal vote or referendum.
"I feel for young people who had their relationships questioned in a way I wouldn't have thought we would see ever again, but nevertheless what this marriage equality survey shows is that unconditional love always has the last word," Labor leader Bill Shorten said Wednesday.
Marriage legislation to be introduced
The result of the survey, conducted by the Australian Bureau of Statistics, was non-binding and, in theory, the Australian Parliament doesn't need to act on it.
However, Turnbull said Wednesday he would keep his promise to hold a free vote -- also known as a conscience vote -- on a bill to legalize same-sex marriage.
A conscience vote means politicians can vote with their electorates or their own opinions, rather than following the usual strict adherence to voting with their party.
Same-sex marriage campaigners say they're confident they have the numbers in the Australian Parliament to pass the legislation.
"The challenge has never been the numbers, we've always had a majority in (this) parliament on marriage equality, just as there's been a majority in the population. The problem has been the will of politicians," Tiernan Brady, executive director at the Equality Campaign, told CNN.
The most popular bill under consideration, written by governing Liberal Party Senator Dean Smith and supported by the opposition Labor Party, was introduced into the Australian Senate late on Wednesday afternoon, just hours after the result, and is due to be debated Thursday morning, a spokesman for Senator Smith confirmed to CNN.
It allows for same-sex marriage but includes religious protections for those who conduct marriages but don't want to officiate LGBT ceremonies.
"As a result of this clear win, (the 'yes' side) have got the numbers and they've absolutely got more momentum than they might have had, had it been a close result," University of Western Australia professor of Politics Peter Van Onselen told CNN.
Conservatives push for protections
Conservatives are expected to fight hard for religious protections in any same-sex marriage legislation.
A second bill, written by Liberal Party Senator James Paterson, was originally touted by conservatives and "no" advocates as an alternative to Smith's.
That bill would have offered business and service providers legal protection if they chose to deny wedding services to same-sex couples.
Paterson announced Wednesday he wouldn't be introducing it to the Senate, but it gives an indication of the kind of religious protections conservatives might push for.
Amy Maguire, senior lecturer in International Law and Human Rights at the University of Newcastle, said Paterson's bill would have applied to "hotels, photographers, florists, bakers and hire car drivers"
"The bill would also permit parents to withdraw children from classes if content is inconsistent with a 'relevant marriage belief' or 'relevant belief'," she wrote on the Conversation website.
Paterson said in a Facebook post after the result
he would push for "amendments" to Smith's bill instead, while former Australian Prime Minister and prominent "no" campaigner Tony Abbott said Smith's bill still needed to be "improved."
"I look forward to a parliamentary process that improves (the bill) to implement same-sex marriage with freedom of conscience for all, not just the churches," he said.
Van Onselen said conservative politicians could play a long game and allow the legislation to be passed by Christmas, with the aim of seeking to amend the law in future.
Brady said any attempt to introduce strict protections such as those in the Paterson bill would be "a rebuke to the people of Australia."
"There is no reason in the world to delay this. This has been a 20-year debate and it's over," he said. "Pass the law."