The National Council of Provinces passed the controversial Civil Union Bill yesterday, paving the way for President Thabo Mbeki to sign the measure into law.
The legislation, intended to afford gay and lesbian couples the same legal status as married heterosexuals, has drawn fierce criticism from opposition parties as well as religious groups.
"By approving this legislation, this house is at odds with the wishes of a majority of South Africans who have overwhelmingly rejected it," said IFP MP Jeanette Vilakazi.
The measure - approved in the national assembly last week - was opposed by most opposition parties. The DA allowed its members a free vote on the issue.
Religious groups had called for both houses of parliament to either consider revising the measure or to scrap it altogether.
With their pleas having been ignored, their only hope now lies with Mbeki.
The president has to sign the legislation for it to become law.
It now remains to be seen if Mbeki will approve the bill, particularly given that submissions made during extensive public hearings indicated overwhelming public discontent over the proposed law.
Parliament has been working to meet a constitutional court deadline of December 1 to correct what the court ruled in December last year was an unconstitutional definition of marriage in legislation. - Sapa