Same-sex marriage was signed into law in Ireland on Thursday, five months after a historic referendum saw the traditionally Catholic nation become the world's first country to vote for gay unions.
In a brief statement, the president's office said "The Presidential Commission today signed the 'Marriage Bill 2015' into law", paving the way for the first weddings within a month.
In May, Ireland voted 62.1 percent in favour of allowing marriage between two people "without distinction as to their sex," the first time anywhere that gay marriage has been legalized by referendum.
Legal challenges to the result had briefly delayed the legislation from coming into effect.
Senator Katherine Zappone, who had long campaigned for her Canadian marriage to her wife to be recognized in Ireland, called it "a defining moment".
"It is a deeply emotional moment for those of us who have campaigned for so long," Zappone said in a statement. "This victory truly belongs to the nation, it is a moment for us all."