The bill to be introduced on Monday would require social media platforms to take reasonable steps to verify users' ages, including by using existing account information, facial technology and digital identity documents.
"We simply cannot accept the harm being done to a generation of New Zealand children," Prime Minister Christopher Luxon said in a statement.
"Social media is exposing them to harmful content, addictive technology and pressures they are not equipped to deal with and it's affecting their family life, mental health, sleep, and education," Luxon said.
It was not immediately clear if the bill would garner sufficient support to pass through Parliament, with one of Luxon's coalition partners, the New Zealand First party, saying it wouldn't support it.
"We have been concerned with the proposed legislation and the direction and slippery slope that legislation like this will inevitably take our country," New Zealand First leader Winston Peters, who is also the country's foreign minister, said in a post on X.
In December, Australia became the world's first country to ban social media for children under 16, blocking them from platforms including TikTok, Alphabet's YouTube and Meta's Instagram and Facebook.
That legislation had been a "colossal failure" Peters said, adding that keeping children off social media should be the responsibility of parents.
"I won't pretend that it will be simple or that it will be perfect," Luxon said at an event.
"We won't get every single child off social media. Some will always find ways around it, but frankly, it's just way too important not to at least try."
