Jacinda was born in Hamilton, New Zealand, Ardern grew up as a Mormon in Morrinsville and Murupara, where her father, Ross Ardern, worked as a police officer, and her mother, Laurell Ardern (née Bottomley), worked as a school catering assistant.
On 20 May 1982, Robert Muldoon announced that New Zealand would make HMNZS Canterbury, a Leander-class frigate, available for use where the British thought fit to release a Royal Navy vessel for the Falklands. The New Zealand government expelled the Argentinian ambassador following the invasion. The Prime Minister, Robert Muldoon, was in London when the war broke out.
Ardern contested the seat of Auckland Central for Labour in the 2011 general election, standing against incumbent National MP Nikki Kaye for National and Greens candidate Denise Roche. Despite targeting Green voters to vote strategically for her, she lost to Kaye by 717 votes. However, she returned to Parliament via the party list, on which she was ranked 13th. Ardern maintained an office within the electorate while she was a list MP based in Auckland Central.
Ardern stood again in Auckland Central at the 2014 general election. She again finished second though increased her own vote and reduced Kaye's majority from 717 to 600. Ranked 5th on Labour's list Ardern was still returned to Parliament where she became Shadow spokesperson for Justice, Children, Small Business, and Arts & Culture under new leader Andrew Little.
Ardern put forward her name for the Labour nomination for the Mount Albert by-election to be held in February 2017 following the resignation of David Shearer on 8 December 2016. When nominations for the Labour Party closed on 12 January 2017, Ardern was the only nominee and was elected unopposed.
On 21 January, Ardern participated in the 2017 Women's March, a worldwide protest in opposition to Donald Trump, the newly inaugurated president of the United States. She was confirmed as Labour's candidate at a meeting on 22 January. Ardern won a landslide victory, gaining 77 percent of votes cast in the preliminary results.
Following her win in the by-election, Ardern was unanimously elected as deputy leader of the Labour Party on 7 March 2017, following the resignation of Annette King who was intending to retire at the next election. Ardern's vacant list seat was taken by Raymond Huo.
On 19 October 2017, New Zealand First leader Winston Peters agreed to form a coalition with Labour, making Ardern the next prime minister. This coalition receives confidence and supply from the Green Party. Ardern named Peters as Deputy Prime Minister and Minister of Foreign Affairs. She also gave New Zealand First five posts in her government, with Peters and three other ministers serving in Cabinet.
On 2 February 2018, Ardern traveled to Waitangi for the annual Waitangi Day commemoration; she stayed in Waitangi for five days, an unprecedented length. Ardern became the first female prime minister to speak from the top marae. Her visit was largely well-received by Māori leaders, with commentators noting a sharp contrast with the acrimonious responses received by several of her predecessors.
On 19 January 2018, Ardern announced that she was pregnant and that Winston Peters would take the role of acting prime minister for six weeks after the birth. Following the birth of a daughter, she took her maternity leave from 21 June to 2 August 2018.
On 15 March 2019, 51 people were fatally shot and 49 injured in two mosques in Christchurch. In a statement broadcast on television, Ardern offered condolences and stated that the shootings had been carried out by suspects with "extremist views" that have no place in New Zealand, or anywhere else in the world. She also described it as a well-planned terrorist attack.
In March 2019, the perpetrator of the Christchurch mosque shootings in New Zealand used Facebook to stream live footage of the attack as it unfolded. Facebook took 29 minutes to detect the livestreamed video, which was eight minutes longer than it took police to arrest the gunman. About 1.3M copies of the video were blocked from Facebook but 300,000 copies were published and shared.
On 14 March 2020, Ardern announced in response to the COVID-19 pandemic in New Zealand that the government would be requiring anyone entering the country from midnight 15 March to isolate themselves for 14 days. She said the new rules will mean New Zealand has the "widest ranging and toughest border restrictions of any country in the world". On 19 March, Ardern stated that New Zealand's borders would be closed to all non-citizens and non-permanent residents, after 11:59 pm on 20 March (NZDT). Ardern announced that New Zealand would move to alert level 4, including a nationwide lockdown, at 11:59 pm on 25 March
On 19 March, Ardern stated that New Zealand's borders would be closed to all non-citizens and non-permanent residents, after 11:59 pm on 20 March (NZDT). Ardern announced that New Zealand would move to alert level 4, including a nationwide lockdown, at 11:59 pm on 25 March.