The first same-sex weddings can take place from 29 March 2014, equalities minister Maria Miller says.
Initially it was thought the first same-sex marriage in England and Wales would not take place until the summer.
Couples wishing to be among the first to marry will need to give formal notice of their intention to marry on 13 March.
It comes after the government's controversial legislation on the issue received Royal Assent in July.
The Conservative, Labour and Liberal Democrat leaderships all backed the proposals.