Speaking on Saturday on the tenth anniversary of the equal age of consent, he said that there was more to do on marriage equality.
Mr Miliband said: “The introduction of civil partnerships was one of the most significant changes introduced by Labour. Those equalities now have overwhelming public support and are being copied by many countries around the world.
“Five years on from the first civil partnership it is right that we look at extending marriage equality for those people who want it. I hope that we can make progress on this during the year ahead.”
He added that more must be done to tackle homophobia in schools and ensure that young people have “positive role models”.
In July, Mr Miliband said he did not think there was enough support for marriage equality.
“I will listen to what people have to say on going further than that if there is a demand. No one has yet put that to me in the leadership election,” he said.
Last month, it was reported that potential reforms to open up both marriage and civil partnerships to all couples were “being discussed” by coalition government ministers.
In a separate move, equality minister Lynne Featherstone is expected to announce plans soon to give gay couples the right to have religious civil partnerships.
Gay rights campaigner Peter Tatchell is to launch a legal challenge against the bans on gay marriage and straight civil partnerships at the European Court of Human Rights shortly.
A Times poll in 2009 found that 61 per cent of the general public were in favour of gay marriage, while a PinkNews.co.uk poll carried out last year found that 98 per cent of readers wanted the right to marry.