The portfolio would cover the spread of nuclear, chemical and conventional weapons.
"The pursuit of disarmament is as vital today as it was when Norman Kirk and David Lange proclaimed New Zealand's opposition to nuclear weapons and nuclear testing in the Pacific," she said.
"Risks to global peace and security are growing. The greatest challenge we have today comes from North Korea, situated right here in our region.
"We must recommit ourselves to the cause of non-proliferation and disarmament, and to the norms and rules which support those endeavours."
She said the Government was looking at the early ratification of the Treaty on the Prohibition of Nuclear Weapons, negotiated at the United Nations last year, which New Zealand has already signed.
In her speech, Ardern also touched on New Zealand's relations with the United States which she described is terms of difference.
She described the relationship with the United States as "fundamental" and said that for over 70 years, the values and interests of New Zealand and the US had intersected more often than not.
"But the real strength of any important relationship lies in its breadth and ability to encompass difference," she said.
"for example, we were disappointed at the United States withdrawal from the Paris [climate change] agreement and some of its positioning on trade.
"But our relationship with the US is certainly robust enough to withstand those differences."
She described China in terms of leadership. She said its leadership on issues such as climate change and trade liberalisation could "add momentum to our collective efforts in those areas."
There were areas in which New Zealand did not see eye to eye with China.
"My Government will speak honestly and openly with our friends in Beijing, whether it is about human rights, pursuing our trade interests or the security and stability of our region.
"Taking that approach isn't about singling countries out but about taking a consistent approach on the issue and principles that matter to us."
