Jacinda Ardern has described the Christchurch Call summit as "day one" in the change the world needs.
At the meeting in Paris overnight, all of the major technology companies, 17 countries and the European Commission signed up to the call to action.
The US was a notable no show - and did not sign up to the agreement.
Prime Minister Jacinda Ardern and French President Emmanuel Macron spoke after the summit.
Ms Ardern says the end result of the Christchurch call has to be a more humane internet.
