The Civil Partnership Bill has passed all stages in Leinster House.
The controversial legislation was supported by 48 votes to 4 in the Seanad this evening after two days of debates on proposed amendments.
It was passed by TDs in the Dáil last week.
The Bill - which will give rights to gay and lesbian couples - will now go forward to the President Mary McAleese who will sign the legislation into law.
Justice Minister Dermot Ahern said the passage of the Bill is a good day for politics.
"It's a proud day for my party that we have been able to bring forward this very progressive piece of legislation," Minister Ahern said.