Same-sex couples could be able to marry in Guernsey by the summer, according to a States senior committee member.
Employment and Social Security Committee Vice President Shane Langlois said the UK Privy Council had given Royal Assent to the local law.
It will go before the States for final approval before coming into effect.
Last year same-sex marriage was approved in Guernsey by a vote of 33-5.
It makes Northern Ireland now the only part of the British Isles without marriage equality, following successful equal marriage campaigns in Jersey and the Isle of Man.
However, Mr Langlois warned against making any wedding arrangements until a commencement date was announced.
Under the legislation, couples will be able to get married in a civil ceremony.
Equality charity Liberate has welcomed the next step in what has been a long process and said it was looking forward to couples being able to plan their wedding.
To date, more than 20 countries have legalised gay marriage:
2005: Spain, Canada
2006: South Africa
2009: Norway, Sweden
2010: Portugal, Iceland, Argentina
2013: Brazil, France, Uruguay, New Zealand, England/Wales
2014: Luxembourg, Scotland
2015: Finland (signed 2015, effective 2017)
2015: Ireland, United States