Labour MP Louisa Wall says she is very happy with the overwhelming support for her bill which would make same-sex marriage legal.
The Marriage (Definition of Marriage) Amendment Bill passed its first reading by 80 votes to 40 on Wednesday night. There were no abstentions.
Ms Wall says the vote was historic moment for New Zealanders and a step toward the legal recognition that couples, regardless of their sex, sexual orientation or gender identity, should be able to marry.
"Obviously I was hoping for 61 votes, so to get a bit more is pleasing," she said. "But this is the first hurdle in the transition from this being a Bill to being an Act, so there's a lot more to be done."
The members' bill was subject to a conscience vote, meaning MPs were not bound to party lines.
National's John Hayes says he got a strong message from his Wairarapa electorate that they feared the bill might lead to the legalising of polygamous or incestuous relationships, so he had to vote against it.
Fellow National MP Paul Hutchison says he thought long and hard about whether to vote for the bill but he simply could not construct a strong enough intellectual, moral, health or even spiritual argument against it.
The national body for Catholic bishops plans to continue to oppose the legislation through public submissions.
Archbishop of Wellington John Dew says marriage should remain defined as between a man and a woman because society does not have the right to deprive a child of its father or mother.