Australia has legalised same-sex marriage after a bill to enact the historic social reform passed Parliament on Thursday night.

After hundreds of hours of debate, the bill passed the House of Representatives, with only four MPs – independent Bob Katter, the Nationals’ David Littleproud, Keith Pitt, and Liberal MP Russell Broadbent – voting against the bill.

“What a day. What a day for love, for equality, for respect. Australia has done it,” said Prime Minister Malcolm Turnbull.

Opposition Leader Bill Shorten said: “The Australia of tomorrow begins with what we do today. At long last, LGBTIQ Australians will be equal under the law.”

Watch actor and Yes campaigner Magda Szubanski celebrate with a signature ‘happy dance’

When the bill passed, the packed public gallery cheered, applauded and sang ‘I Am Australian’, while MPs unfurled rainbow flags and politicians from all sides embraced.

The marriage bill is expected to be ratified by the Governor-General on Friday, but the first gay weddings in Australia are not likely to happen until next year.

That is because, under Australian law, couples must give 30 days’ notice prior to a wedding. It means gay weddings are likely to take place from January 8 next year.

Earlier, a final vote was delayed as politicians voted on a string of amendments aimed at protecting religious freedoms.

Late into the debate, as it became clear those amendments were likely to fail, Mr Katter and National MP Andrew Broad gave combative speeches in which they hit out at LGBTI advocates.

Mr Katter, who had previously said he would not be spending any more time on same-sex marriage, emerged as the key figure delaying the process at 5pm on Thursday.

Despite audible groans from the Parliament as he rose to his feet, Mr Katter offered two bizarre speeches that touched on issues as diverse “men wearing dresses” and Mao Zedong’s Little Red Book.

“I think you have a damn hide and an inflated opinion of yourself as well,” he told LGBTI advocates in the gallery.

“The rest of the world would agree with me. They took the word gay off us and now they are taking the word marriage of us.”

Mr Broad compared the freedoms he believed would be lost if the bill passed unamended to allowing his daughter to walk into a home and play her electric guitar as loudly as he wanted.

“If you wouldn’t give that freedom away in your own home, don’t take it away from the churches and religious organisations of Australia,” he said.

As occurred in the Senate last week, most amendments from Coalition conservatives aimed at bolstering legal religious protections were voted down by a cross-party group of Coalition, Labor and crossbench MPs.

Bob Katter made a number of bizarre contributions during the debate. Photo: AAP

Those included a proposal to create two separate definitions of marriage, to allow new civil celebrants to refuse to marry gay couples, and to protect religious charities from losing their tax-exempt status if they publicly oppose same-sex marriage.

Same-sex marriage advocates argue that charities would not have been adversely affected by the bill, and some said that religious freedoms could be considered under a review to be conducted by Philip Ruddock next year.

Labor’s Deputy Leader Tanya Plibersek hit out at the delay as the debate dragged on, saying the amendments were completely unneccessary.

Labor MPs warned that amending the bill would mean it would have to return to the Senate, meaning was unlikely to pass on Thursday.

The Turnbull government promised to hold a free vote on same-sex marriage if the postal survey returned a ‘Yes’ vote. The Australian Bureau of Statistics announced last month that Australians voted 61.6 per cent for ‘Yes’, compared with 38.4 per cent for ‘No’.

Prominent ‘Yes’ campaigners, including comedian Magda Szubanski and Sydney Liberal councillor Christine Forster, held a final rally outside Parliament House on Thursday morning.

They were in the chamber for Thursday’s debate, alongside Olympic swimmer Ian Thorpe.

Nationals MP Andrew Broad referenced his daughter’s electric guitar playing during the debate. Photo: AAP

Gay couples who were married oversees will also have their marriages immediately recognised by Australian law.

As the debate dragged on into Thursday afternoon, Coalition members accused the opposition of binding the Labor caucus on each vote.

“We have the situation in the Labor party where the idea of a conscience vote has been completely thrown out the window,” said conservative Liberal MP Kevin Andrews.

Labor MP Terri Butler said if amendments were agreed to the bill would be delayed, which the Australian people would not tolerate.

Throughout the debate, ‘Yes’ supporters sitting in the public gallery cheered and clapped after the amendments were voted down.

Speaker Tony Smith asked for the gallery to show respect but said he would grant a degree of latitude given the “historic nature” of the legislation.