Ardern began by recalling being booed for mentioning global warming at an election debate in Morrinsville 10 years ago, joking that her grandmother was among those booing her.
She spoke of the effects of climate change on the Pacific Islands, saying the extreme weather events and rising sea levels put some islands at the risk of extinction.
She said New Zealand was at the forefront of women's suffrage, the welfare state, and had taken a principled stance within the UN on matters from commercial whaling to nuclear weapons.
She said she would like to think New Zealand would be a leader on climate change - but others were also needed.
"I hope each of us can look back on this period of time and say that we were on the right side of history."
Ardern also took questions from the audience, ranging from the prison population to how Maori were being included in climate change efforts and whether it was difficult to keep emissions low given the travel distances to New Zealand. She was also asked how she could go about winning other international leaders to climate change action, such as US President Donald Trump.
To that, Ardern said she preferred to focus on what was possible - and referred to New Zealand's tricky situation included transport:
"We don't have a natural inclination to use public transport partly because we didn't build it."
However, she said the biggest was agricultural emissions.
Ardern was given a glowing welcome by Sciences Po President Frederic Mion, who said she was something of a role model for the students due to her youth - and "the way you are reconciling pregnancy and the leadership of your country".
He referred to the euphoria over the Paris Agreement being tempered by international upheaval from Brexit, the election of US President Donald Trump, the terror attacks in Europe including France.
"As is sometimes, if not always, the case hope springs up again in the guise of youth," he said.
He referred to the election of Canada's Prime Minister Justin Trudeau, France's Emmanuel Macron and then Ardern in quick succession.
Ardern was described as "an inspiration" by an American student and gifted a present for her baby by one of the New Zealand students in the audience.
Earlier, Ardern was welcomed at the Élysées Palace in Paris with a guard of honour by the Republican Guard.
Macron greeted her with a handshake, placing his other hand over hers and guiding her inside with a hand on her back.
In the meeting room, they posed for photos and Macron spoke to Ardern in English, saying he was happy to have her in Europe.
Macron has given France's approval for the EU-New Zealand free trade negotiations to begin in earnest.
Macron voiced support for the trade negotiations after meeting with Prime Minister Jacinda Ardern at the Élysées Palace this morning, saying it could set the standard for a "new generation" of trade agreements which included social responsibility.
He said he and Ardern had agreed that trade agreements should address social responsibility.
"I believe there is a new generation of trade agreements we can take forward and the agreement between the EU and New Zealand can set a standard."
The European Council is expected to decide on the mandate for talks to begin in May and Ardern wanted to ensure Macron was on board because of sensitivities around agriculture in France. Ardern had urged him to let those issues be resolved through negotiations.
In return, he had asked for New Zealand's support in the fight against Isis or Daesh.
He thanked Ardern for an invitation to visit New Zealand - and spoke of the close relations between the two countries although there was some "friendly confrontation"
In rugby with a tour planned in June.
Macron indicated he was open to visiting New Zealand, saying he "would have occasion" to visit after the PMs invitation. However he did not indicate when that might be.
If he takes up the invitation it will be the first ever visit by a French President to New Zealand. In May Macron is due to visit New Caledonia before its self-rule referendum and then Australia, but hopes are low that he will be able to fit New Zealand in at that time.
In a statement after the meeting, the two leaders agreed to enhance bilateral trade - including "through the future negotiation of a balanced, mutually beneficial, progressive and inclusive free trade agreement between New Zealand and the European Union."
It also includes a mention of the need for a strong WTO - a measure to send a signal as protectionism rises through the "trade wars", especially between China and the United States.
The agreement specified that that should preserve the rights of government to regulate for public policy objectives - reflecting the concern of both the EU and New Zealand about Investor States Disputes Settlement processes.
The statement was also heavy on climate change statements - a priority for both Ardern and Macron.
But Macron's concerns about terrorism were also reflected in an anti-terrorism clause in which the leaders committed to "upholding our fight against terrorism worldwide, particularly in the Middle-East, South-East Asia and Africa both on the ground and by sharing information on regional developments."
France has been the subject of several terrorist attacks. Ardern is due to decide on the future of deployments to Iraq and Afghanistan in the near future.
Macron and Ardern held a press conference in the "winter garden" area of the Salle des fetes - the palace ball room at which state dinners and functions are held.
It was a far cry from the more industrial look in the Beehive, with multiple chandeliers and gilded cherubs gazing down from above.
Ardern said New Zealand and France had shared a long relationship.
"My discussions with the President this morning have confirmed our relationship, but the importance of that relationship has grown in recent times."
She said that was a result of global uncertainty where people were looking for leadership.
She said they discussed the global fight against terrorism and climate change "and our concerns around the rising tide of protectionism".
She believed they were "natural partners".
She praised Macron for his action on climate change, including securing the Paris Agreement. "I also conveyed New Zealand's desire to work more closely in these areas."
"We've agreed to extend our cooperation into the area of climate-friendly agriculture," meaning technology that helped reduce the emissions of food production.
Ardern welcomed Macron's support for that agreement and also spoke of allowing it to include issues such as climate change.
"I hope the EU FTA agreement with New Zealand will be a model of what is possible in that regard."
She reiterated her invitation to visit, saying she looked forward to reciprocating his hospitality.
Asked by French media about the issue of agriculture, Ardern said New Zealand already fell short of its quota for trade with the EU and at this stage was simply seeking to be at the table.
Ardern's trip
Prime Minister Jacinda Ardern also meet Canada's Prime Minister Justin Trudeau overnight followed by German Chancellor Angela Merkel in Berlin later today.
On an overcast day in Paris it was very much the days for the young ones - Ardern, Trudeau and Macron are part of the small "under 40s" club of world leaders - those elected when they were under 40.
Their age has ensured they captured attention - including Ardern, who had a piece on climate change published in Le Figaro.
Ardern went to Paris with business on her mind - seeking Macron's support for a free trade deal with the EU. But it was also a relationship-building mission to ensure New Zealand has influential friends in the EU after it loses its primary champion - the United Kingdom. France and Germany are key to that.
Ardern will not meet Macron's wife Brigitte or share personal time, such as a dinner, with him but the 45 minutes allocated for the meeting was a positive sign.
Macron, Trudeau and Ardern have more than age in common - all have also put climate change at the top of their political platforms and are advocates for the Paris Agreement.
Macron and Ardern can claim credit for forging ahead - Macron's move late last year to halt all oil and gas production in France from 2040 was cited by Ardern when she announced there would be no future block offer permits for offshore exploration and mining.
Ardern's meeting at the Élysées Palace was expected to canvas the free trade agreement between New Zealand and the EU, the unfolding situation after missile strikes by France, US and the UK in Syria. Ardern is hopeful that will act as a catalyst for change on the veto powers of the Security Council.
Five things about French President Emmanuel Macron:
• Aged 40 and married to his former teacher Brigitte Trogneaux
• Was 39 when elected President of France, his first elected position.
• Adopted a climate-change motto of "Make the Planet Great Again" in an ironic dig at US President Donald Trump for pulling out of the Paris Agreement.
• Sent Chinese President Xi Jinping a Republican Guard horse called Vesuve de Brekka
• A tactile leader, he likes to hug and put his arm around other leaders.
