The resounding yes vote for marriage equality is a "victory for love" and demonstrates South Australia's "natural sense of justice", Premer Jay Weatherill says.
The premier joined hundreds of supporters of same-sex marriage in the centre of Adelaide on Wednesday to hear the results of the postal survey with 62.5 per cent of South Australians voting yes, slightly higher than the national result of 61.6 per cent.
"It's an extraordinary relief for many of us who have been supporting marriage equality for an extended period of time," Mr Weatherill said.
"But what a shocking waste of $100 million.
"Sadly we had to go through this very expensive exercise to tell everybody what they already understood, that there was strong majority support for marriage equality."
South Australian Dignity Party MP Kelly Vincent said for her the vote meant that all the pain she went through as an adolescent coming out was worth it.
"As a policy maker it also means we can move on with our jobs of making Australia and fairer and more equal place for everyone," she said.
Other supporters of same-sex marriage said they were relieved by the vote but still concerned that the federal government would continue to stall on passing the legislation.
Mr Weatherill said the government should move immediately to bring the necessary measures before parliament.
"Some people won't give up their opposition," he said.
"But now there's the strongest possible mandate for every parliamentarian to look at the results in their electorate and understand that the overwhelming majority want marriage equality.
"They should just get on with that."