The Presidential Commission has signed the Marriage Bill 2015 into law, according to a statement from Áras an Uachtaráin.
The commission consists of Chief Justice Susan Denham, Dáil Éireann Ceann Comhairle Sean Barrett and his Seanad counterpart Senator Paddy Burke.
President Michael D Higgins is currently on a State visit to the west coast of the United States, where he planted at tree to commemorate those who died in the Berkeley balcony collapse.
The Bill passed through the Seanad last week, with the presidential endorsement meaning it has cleared the final hurdle.
Last week, Minister for Justice Frances Fitzgerald said that soon we will have Christmas weddings of people who thought they would never be allowed to marry.
She said the first same-sex marriages in Ireland will take place from the middle of November.
Ireland became the first country in the world to bring in same-sex marriage by popular vote in May when 62.1% of voters supported the same-sex marriage referendum.