The 37-year-old prime minister has landed in Auckland on a visit for the trans-Tasman nations this week, meeting with New Zealand prime minister Jacinda Ardern.
It is the first time a sitting Finnish PM has visited either country.
Ms Ardern said she particularly valued the insight of Ms Marin into the impacts of Russia's illegal invasion on Ukraine, given Finland shares a border with Russia.
"We discussed our strong commitment to supporting Ukraine as the war continues. The conflict I'm very aware is literally on Finland's doorstep," Ms Ardern said.
Ms Marin said the deteriorating geopolitical environment meant "we need to make sure that democratic countries are working together even more closely".
"We have to make sure that we have the trading routes, that we have cooperation also in the international fora that we need in the future even more so because we are also seeing the pushback of human rights," she said.
"We are seeing authoritarian countries having their own ideologists in place and the situation is getting more severe.
"So we need democratic countries and the cooperation between democratic countries.
"The Nordic countries together, Australia and New Zealand we could tighten our cooperation so much more."
New Zealand hopes to bolster trade with the EU after agreeing a free trade agreement in June.
Australia is also negotiating a similar deal but is yet to reach agreement.
Ms Marin welcomed the chance to deepen trade with democracies.
"I really worry about the dependencies that we have right now on authoritarian countries when it comes to new technologies, the digital infrastructure in our societies," she said.
"(We have to) make sure that we are not building the same traps when it comes to new technologies and digital solutions that we have right now in Europe when it comes to energy from Russia."
Her comments are most likely a reference to both Russia, but also China, New Zealand's biggest trading partner.
Ms Marin is best known outside Finland as a "party PM" due to her attendance at rock festivals and leaked videos of her dancing with friends: normal activities for a woman her age, but not necessarily associated with high office.
She rebuked a journalist for asking whether she had accepted the mantle, saying "I don't focus on it".
"I focus on other issues ... the global pandemic. There's war now in Europe. The energy crisis. Perhaps an economic crisis," she said.
"If the media wants to focus on (my behaviour) I don't have anything to say. You are free to discuss and write what you want but I'm focusing on the issues."
Ms Ardern backed Ms Marin, telling the journalist "I think (your) readers probably would be focused on the issues as well".
Another journalist asked whether they were meeting because of their similarities, including age.
"I wonder whether or not anyone either asked Barack Obama and John Key if they met because they were of similar age," Ms Ardern queried, suggesting a sexist framing.
Ms Marin put it more manner of factly.
"We are meeting because we are prime ministers," she said.
After two days in New Zealand she will head to Sydney for similar talks with Anthony Albanese.
