Same-sex couples who have already married overseas will have their relationships recognised in Australia from midnight tonight.

Key points: Governor-General signed off on same-sex marriage bill this morning

Governor-General signed off on same-sex marriage bill this morning Existing marriages performed overseas to be recognised at midnight, and new weddings can be registered from then

Existing marriages performed overseas to be recognised at midnight, and new weddings can be registered from then George Brandis described yesterday as unforgettable, Malcolm Turnbull says moment "belongs to whole parliament"

After the drama and excitement of the same-sex marriage bill passing the House of Representatives chamber yesterday, the Governor-General signed off on it this morning.

Attorney-General George Brandis said couples had to give a month's notice of their intention to marry, so the first same-sex weddings will be able to happen from January 9.

Senator Brandis said he became quite emotional when the bill passed and the public galleries erupted with cheers and singing.

"To see the galleries of the House of Representatives just explode spontaneously was unforgettable," Senator Brandis told AM.

He said he had celebrated with his Labor counterpart Penny Wong last night.

"I saw Senator Wong at an event and we did have a drink, which doesn't happen very often, but it was a completely non-partisan achievement. This is not owned by the Liberal Party or the Labor Party or any political party. It is owned by the Australian people," Senator Brandis said.

"The Parliament effectively spoke with one voice to give effect to their wishes."

Sorry, this video has expired An emotional George Brandis describes the same-sex marriage vote as "unforgettable"

But Prime Minister Malcolm Turnbull said Labor was taking credit for the result.

"The Labor Party voted for it and that was good but they did everything possible to stop it happening, they did everything possible to stop people having their say," Mr Turnbull told Channel Seven.

"That was just plain, petty politics. Look they had six years in government and they did nothing about it.

"This is a Liberal-National government, I am a Liberal prime minister and we have made it happen, but it belongs to everybody. It belongs to the whole Parliament and above all to the whole country."

Senator Wong responded to that comment by tweeting that it was "such a shame that Malcolm's desperation diminishes this moment of national joy".

Sorry, this video has expired Cheers and singing as SSM vote passes in the Parliament

PM 'didn't notice' Abbott abstained

The bill passed with overwhelming support in the Lower House.

Four MPs voted against and some, including former prime minister Tony Abbott, abstained.

Mr Turnbull said he had not noticed that Mr Abbott was not in the chamber when the final vote was taken.

"I didn't notice his absence — was he not there?" he asked AM host Sabra Lane.

"Well, it is a free vote. In our party a free vote means you can vote for or against or abstain if you wish."

Only four members of the House of Representatives voted no. ( ABC News: Matt Roberts )

The legislation passed without any of the amendments to increase exemptions for charities or religious groups.

Mr Turnbull said he was confident about the legislation in its original form.

"I am quite satisfied that this change will not put religious freedoms at risk and it certainly doesn't put traditional marriage at risk," he said.

The PM said same-sex marriage would not harm his marriage.

"Two gay people getting married is not going to put Lucy and my nearly 38-year-old marriage under threat, I can assure you," he said.

"People who think that gay people making a commitment is a threat to marriage, fail to recognise that the real threat is lack of commitment.

"So more commitment, more marriage, is good."