The poll was published a day before the results of a national vote in Australia on legalising same-sex marriage are due to be announced...
The poll was published a day before the results of a national vote in Australia on legalising same-sex marriage are due to be announced, and found that rugby and football fans were most supportive of the governing bodies speaking out on the issue.
Australia has lagged behind its international peers in legalising same-sex marriage, amid political divisions over how to legislate the changes.
The conservative government opted for a voluntary national survey and said it would move a bill in parliament if there is, as expected, a majority "yes" vote in support of gay marriage when the results are announced on Wednesday.
Sport plays in a central role in Australian culture, and major governing bodies -- including for rugby union, soccer, cricket and Australian Rules football -- have publicly supported the "yes" camp.
Across the Australian public, there is also broad public support for same-sex unions.
The YouGov/Monash University survey of "superfans" -- fervent sports supporters -- found Australians aged 18 to 34 were 71 percent in favour of the organisations' public stance.
Some 56 percent of Australians aged 35 to 54 were in support of sporting codes airing their pro-equality views, but more than half of those over 55 said it was wrong.
A total of 1,003 respondents in Australia were surveyed.
"This research shows the majority of Australians, particularly core sport fans, support the big sports taking a stance on gay marriage," Monash University's Behavioural Science Laboratory director Kerry O'Brien said in a statement.
"They should be encouraged to lead in other areas as well."
Popular rugby union star David Pocock, who was born in Zimbabwe, has been a strong proponent of sporting bodies speaking out on important social issues.
"Sport is at its best when it's challenging society to become more inclusive," the Wallaby said in a statement released by his agent on Tuesday.
"As a child growing up in southern Africa, seeing how President (Nelson) Mandela used the Rugby World Cup to try and unite a country so recently freed from apartheid, I've been keenly aware of this most of my life."
Despite growing support among sporting bodies for marriage equality and homosexual rights, few Australian athletes have come out as gay.
Discrimination and homophobia remain widespread in sport, according to an Australian-initiated survey in 2015 of respondents mostly from Australia, Britain, Canada, Ireland, New Zealand and the United States.