MPs will be asked to vote on an amendment to ban the testing of cosmetics on animals.
The Green Party will introduce the supplementary order paper to the Animal Welfare Act, when an amended bill is up for debate again in its committee stages.
Last year, MPs voted to ban the use of live animals in the testing of legal highs.
The Greens' animal welfare spokesperson Mojo Mathers said there was widespread public support for the animal testing ban on cosmetics.
But she said to get the change the National Government needed to get on board because of the numbers in the House.
"At the moment, they've been sitting on the fence," she said.
But Ms Mathers said there was no excuse now for the Government to vote against it.
"I have worked with lawyers, and with organisations overseas to clear up any perceived technical issues, so that the change would meet legal requirements. It will ensure that there are no unintended consequences."
Ms Mathers said New Zealand would become the first country in Australasia to outlaw testing cosmetics on animals.
"If the Government doesn't vote to support the ban then it will set our international reputation backwards. They will be wondering who the Government is trying to protect in leaving that legal loophole open."
Four of the world's largest animal welfare organisations have written to the Minister for Primary Industries Nathan Guy, urging him to support the ban.
The Humane Society, the International Fund for Animal Welfare, the Royal Society for the Prevention of Cruelty to Animals and World Animal Protection have made the joint plea.
They wanted New Zealand to follow the lead of the European Union, Norway and India, and become the first country in Australasia to outlaw testing cosmetics on live animals.
They said by banning the act the government would live up to its reputation as a global leader in animal welfare.
They said if it did not, the country would be the first and only one in the world to reject the opportunity.