"Over the next five years, we will collaborate to build systems that every farmer will be able to use to measure, manage and reduce their own farm's emissions," Ms Ardern told the summit in New York.
"We are determined to show that New Zealand can and will be the most sustainable food producer in the world."
"The situation is stark. It will not be easy."
New Zealand produces 0.17 per cent of global emissions, but Ms Ardern said they were determined to play their part in the global effort.
Her speech comes as her government tries to push a "Zero Carbon Bill" through parliament, but Greenpeace New Zealand labelled her pledges as "nowhere near enough".
"An appropriate response to the climate emergency would include a commitment to immediately end new fossil fuel exploration on land and at sea, alongside a timeline for rapidly winding down the coal, oil and gas industries," executive director Russel Norman said.
About 60 world leaders are attending the meeting, but the speakers' list does not include Australia as the government has resisted pressure to increase its Paris Agreement targets.
Prime Minister Scott Morrison told reporters in Chicago that he would stick with the original Paris Agreement commitment to reduce carbon emissions by 26-28 per cent on 2005 levels by 2030.
Fiji Prime Minister Frank Bainimarama warned that limiting the temperature increase to 1.5 degrees Celsius in line with the Paris Agreement was not enough to protect Pacific Islands from the "living nightmare" of climate change.
"The brutality of our changing climate has already driven vulnerable communities into a nightmare scenario, one in which the hellscape of storms like Cyclone Winston and Hurricane Dorian have become the new normal," Mr Bainimarama said.
"Acceptance of this living nightmare is morally unthinkable, and denial is unconscionable."
Marshall Islands President Hilda Heine urged other countries to follow its lead and commit to reaching net-zero emissions by 2050.
"The summit must be the moment we choose survival over selfishness, communities over coal, and planet over profits. It must be about climate justice," Ms Heine said.
"To sustain action into the long-term, next year countries must submit their plans to increase ambition by 2030 and to reach net-zero emissions by 2050.
"This is the lens through which history will judge this summit and all of us. The time has come for leaders to do just that, lead."