The Cabinet will today give approval for the Marriage Equality Bill - paving the way for the first official ceremonies by the end of the year.
President Michael D Higgins signed the Marriage Equality Bill into the Constitution at the end of August.
The Government will approve the constitutional change when ministers gather today for the last Cabinet meeting before the Coalition returns for the final Dáil term before the general election.
Justice Minister Frances Fitzgerald was due to bring the Marriage Bill 2015 before her colleagues this morning.
The bill will go through a number of stages in the Dáil and the Seanad, which could take several weeks. The legislation will ultimately be voted on by all members of parliament.
"The first same-sex marriages will be those of couples who convert a notification of their intention to register a civil partnership into a notification of their intention to marry," a Justice Department spokesman said.
He added: "The aim is to have the bill enacted as quickly as possible, subject to the legislative process, so that the first same-sex marriages can take place this year."
The Marriage Equality Referendum was passed by an overwhelming majority, with more than 60pc voting in favour of the change to the Constitution.
The result made Ireland the first country in the world to introduce gay marriage by a popular vote.
The vote was welcomed by gay and lesbian rights groups across the globe.
A legal challenge was mounted against the referendum result but it was shot down by both the High Court and the Court of Appeal.
The two individuals who brought those cases have since lodged an appeal with the Supreme Court.
The applicants, Clare electrician Gerry Walshe and Kilkenny gardener Maurice J Lyons, have complained the views of those opposed to same-sex marriage were not taken into account by the Government during the referendum campaign.