Typically, parties must form alliances to govern, but this time there's a chance Ardern and Labour will be able to go it alone.
Before the 2017 election, Ms Ardern, a young and relatively unknown leader, stunned the nation during the campaign as she gained huge personal support in a phenomenon labelled "Jacindamania".
"We are living in an increasingly polarized world, a place where, more and more, people have lost the ability to see one another's point of view", she said. A day before the election, nearly 2 million people had already cast their vote, representing more than 60% of the total number of votes cast in the 2017 general election.
In terms of Ms Ardern's campaign and victory, Mr Gayford said he was elated with the result. There is now no community spread of the virus in the nation of 5 million and people are no longer required to wear masks or social distance.
Her empathetic and calm leadership style - as well as the fact that she gave birth while in office, the second elected head of government ever to do so - made Ardern an internationally popular figure.
That was despite Ardern's growing global fame and her handling of the Christchurch mosque massacres, which claimed 51 lives and stunned a nation with low rates of gun crime.
Preliminary results won't be released until the end of the month, but if the measure passes, then New Zealand would join Canada, Georgia, South Africa and Uruguay on the list of countries to have legalized consumption of pot on the national level.
With New Zealand having the advantage of being an isolated island nation, the strategy worked.
Earlier this year, Ms Ardern moved swiftly to quell the outbreak by imposing one of the world's most stringent lockdowns. The only new cases found recently have been among returning travelers, who are in quarantine.
The election was originally scheduled for September 19, but it was postponed by a local coronavirus outbreak in Auckland that has since been contained.
The center-right National Party, which governed from 2008 to 2017, trailed with 35 seats, and the Greens had 10 - the same number as the right-wing ACT Party.
Ardern's brand of compassionate politics - "be kind", became her catchphrase during the pandemic - has been championed in sharp contrast to the polarizing approach of President Trump, with whom she has occasionally butted heads. Collins, 61, was promising sweeping tax cuts in response to the economic downturn caused by the virus.
Ms Collins last night congratulated Ms Ardern on an "outstanding" result. It's the best showing for the Labour party in at least 50 years. "I promise you, the National Party will be a robust opposition".
The election also saw Deputy Prime Minister Winston Peters and his small New Zealand First party voted out. Coalition governments there are the norm and no single party has won a majority of votes in 24 years.
Declaring victory in front of cheering party members in Auckland, Ardern said it was clear that Labour had achieved a strong result. "She also really emphasized that unity message, and said she was aware that many voters had voted Labour for the first time". Preliminary referendum results will be released on October 30, and the official results of the election and referendums will be released on November 6, according to the Electoral Commission.