His call goes further than the policy being proposed by the Tory-Lib Dem coalition Government that only proposes to allow gay marriages in civic settings.
He made the statement in a video for the Out4Marriage campaign.
But supporters of traditional marriage have accused all party leaders of playing politics with marriage and being out of touch with the priorities of ordinary people.
Colin Hart of the Coalition for Marriage said, “Party leaders should stop using the institution of marriage as a political weapon to beat their opponents. Poll after poll shows that a majority of the public oppose these changes. Voters have not had the opportunity to have their say and even within the gay community, it is not a priority."
Mr Miliband said faith groups who, "want to provide that opportunity for gay couples … should be able to do so.”
Ministers are consulting on allowing civil marriages for same-sex couples.
Leading Churches oppose calling gay partnership ceremonies marriages, saying they would undermine the status of marriage.
Mr Miliband said, "I think, whether you are gay or straight, you should be able to signify your commitment, your love with the term marriage. We will be pushing the government to get on with the process for legislating for equal marriage, and we'll also be saying to them, where faith groups want to provide that opportunity for gay couples as well as straight couples, they should be able to do so.”
Meanwhile, it has emerged that the Christian owners of a bed and breakfast have received a series of hate-filled messages in the wake of refusing to give a homosexual couple a double room in their guesthouse.
Mike and Susanne Wilkinson say, “hundreds of emails an hour,” came in from around the world, as well as phone calls and texts, some that were very explicit, according to the Daily Mail.
According to the Wilkinsons, they received threatening messages from people who said they would, “come and get them,”
Speaking to the Daily Mail, Mr Wilkinson explained, “One was hand-delivered and handwritten in capitals and said ‘I am coming to burn your house down’ and then lots of filthy words about what they thought of us.”
He added, “It was very scary. And we’ve guests as well as children living here. People started cancelling the bookings. And that’s when we called the police.”
However the police, despite searching through thousands of messages, were unable to track down any of the senders.
There is no suggestion that any of the messages came from the homosexual couple who were refused a room.