UK Prime Minister Theresa May has called on the Australian Government to legalise same-sex marriage quickly in the wake of the Yes vote in the non-binding postal survey.
During Prime Minister's questions in Parliament, gay conservative MP Iain Stewart asked Mrs May if she welcomed the result and whether she hoped "the Government of Australia will quickly legislate".
"I'm very happy to join my honourable friend in welcoming that vote," she replied.
"I hope the Australian Government will indeed take that vote and act on it very soon."
Former UK prime minister David Cameron has also tweeted his approval.
He was leader when same-sex marriage was approved by British MPs in 2013 and faced opposition from within his own party.
"I am a strong believer in marriage," he said at the time.
"It helps people commit to each other and I think it is right that gay people should be able to get married too."
Marriage is an issue devolved to local assemblies in parts of the United Kingdom.
But Northern Ireland is the only place in the UK where same-sex marriage is not recognised.
There the socially conservative Democratic Unionist Party has promised to continue to block it in the near future.
Even if it is defeated in the local Parliament, the DUP plans to prevent any change by using a special mechanism set up to ensure political power sharing in the once troubled region.
