The Brighton Unitarian Church has become the first church in Brighton and Hove to be licensed to conduct civil partnership ceremonies.
The move follows a change in the law which came into force at the end of last year.
The church, in New Road, Brighton, has previously blessed couples in a same-sex partnership.
And if the law is changed to allow same-sex marriage, it is expected to apply to conduct gay weddings.
A bill – or draft law – to permit same-sex marriage has been passed by the House of Commons but has yet to be debated in the House of Lords.
The Brighton Unitarian Church said on its website that several Unitarian churches elsewhere in Britain were already licensed to conduct civil partnership ceremonies.
But it believed that it was the first church in Brighton to be given permission to hold civil partnership services.
Minister Jef Jones said: “I’m chuffed that we’re the first religious venue in Brighton to be able to register civil partnerships.
“We’ve been offering same-sex partnership blessings for years and I’m glad that we’ve taken the next step because it’s very important to many people in this city.”
Councillor Geoffrey Bowden, chairman of the council’s Economic Development and Culture Committee, said: “This is fantastic news and definitely a step in the right direction.
“I look forward to the first civil partnership being held at the church.”