The laws to allow full civil marriage for same-sex couples have completed their journey through the Oireachtas.
The Marriage Bill is now ready to be signed into law next week.
Marriages can then begin as soon as a commencement order is signed, which could take place within a fortnight.
Justice Minister Frances Fitzgerald welcomed what she said was a momentous moment for Ireland.
She said: "Marriage, a cherished institution has been adopted for a new era, but retains its fundamental character.
"Importantly, as a result of the Constitutional amendment couples across this country will gain the protection of the Constitution and its defence of their rights.
"I would say that on the 22nd of May, 2015, the green jersey turned rainbow."
The Irish Council for Civil Liberties (ICCL) has hailed the passing of the act as a "ground-breaking moment" in the protection of human rights and equality.
Speaking at Leinster House shortly after legislators completed their work, ICCL Executive Director Mr Mark Kelly, said: "Five months ago, 1,201,607 people voted to bring an end to marriage discrimination against same sex couples. It is laudable that, notwithstanding the spurious legal cases subsequently brought by individuals opposed to equality, the Government has acted swiftly to make marriage equality the law of the land.
"Ireland has been changed for the better by marriage equality and the social movement created by Yes Equality 2015 is being harnessed to bring about other much needed reforms."