After she took control of Labour, the party surged in the polls, leading the press to coin the term "Jacindamania".
The government's 100 days plan would stay "broadly stay the same" she said, and would include raising the student allowance by NZ$50, banning overseas speculators from buying existing houses, setting up ministerial inquiries into the mental health crisis and historic abuse of children in state care, and passing the healthy homes bill legislating that rental homes be dry and warm.
Julia Gillard, former Labor Prime Minister, also praised Ardern and her party, saying the coalition government was "a great result".
Ms Ardern has now had a call from British Prime Minister Theresa May in which she said they discussed subjects important to both countries.
Later, when a NZ Labour politician became embroiled in the Barnaby Joyce citizenship saga, Ms Ardern was forced to respond to Australian Foreign Minister Julie Bishop's suggestion that she would find it hard to work with a NZ Labour government.
But she kept the celebrations low-key on Thursday night after ending Labour's nine years in the wilderness.
Explosion near mosque kills 10 in Afghanistan's Ghor province
Two of the attacks happened in mosques in Kabul in August and September. Security forces cordoned off the area one hour after the explosion.
The charismatic 37-year-old received a standing ovation from the Labour caucus after forging a coalition with minor parties on Thursday to clinch victory in the September 23 election.
When the ballots were counted, National won the popular vote, claiming 56 seats, with Labour on 46 and the Greens with eight under the country's MMP system.
This story was first published on CNN.com, "Jacinda Ardern to become New Zealand Prime Minister".
Ardern was speaking on TV3 show The Nation. "That is why we believe that capitalism must regain its responsible, its human face". "People can't go shopping with your values", Mr English quipped during one television debate.
Like the rest of New Zealand, Ardern was left in the dark before the announcement by Peters.
Speaking to reporters at the New Zealand Parliament, known as the Beehive, Peters was scant on details about the agreement with Ardern's party, but hinted he could become deputy prime minister.
Asked how he rated Ardern, English noted her rapid rise.