In August, gay and transgender couples will be able to say "I do", choose whether they will be called a bride, bridegroom or partner and legally adopt children. The milestone marks a social revolution which began with the decriminalisation of homosexuality in 1986.
Northland's two National Party members of Parliament, Phil Heatley and Mike Sabin, voted against people having the legal right to be pronounced wife and wife or husband and husband in matrimony.
"I was not surprised at the outcome because there had been such a fervent push beforehand from the people supporting this," Mr Heatley.
He stood by his earlier assertions that marriage was between a man and a woman, he said.
In the conscience vote for the "redefinition", Northland's only other elected MP, Hone Harawira (Mana Party) voted yes, as did two list MPs who live in Northland, Shane Jones (Labour) and David Clendon (Green). Five of the country's six openly gay MPs voted for the bill.
At the amendment's second reading last month, Mr Sabin said he would rather see a national referendum held than have individual MPs vote on changes to the marriage laws.
While people in New Zealand can now marry someone of the same sex the law still forbids marrying a family member, a person under the age of 16 or someone already married. But marriage law reform is not new. Until 1933 the legal age for consent and marriage in New Zealand was 12 years old for a girl and 14 for a boy.
The gay marriage debate has raised interesting reactions in the media. A Northland man wrote a letter to editors saying MPs should not bend over backwards simply to please gay members of their parties; National MP Tau Henare predicted a boost to tourism from Australian gay or transgender couples crossing the Tasman to get legally married in New Zealand.