The law adds a 12th day of public holiday to New Zealand's working year, recognising the Māori body of knowledge around the period on the Māori lunar calendar.
The Te Pire mō te Hararei Tūmatanui o te Kāhui o Matariki/Te Kāhui o Matariki Public Holiday Bill passed its third reading without the support of National or Act.
The bill sets dates for the holiday date through until 2052, falling on the Friday closest to the Tangaroa lunar phase - when the last quarter-moon rises - of Piripi, a period typically falling between June and July.
It marks the beginning of the Māori New Year, the most significant celebration in the traditional Māori calendar - an environmental calendar system which accounts for the position of the sun, heliacal rising of stars, lunar phases, and regional ecological events.
Plans are under way for nationwide events to help support the celebrations.
Matariki brings a focus on remembering those who have died, celebrating the present, and looking ahead to the future and the coming season, though the stories told, traditions honoured and exact timings differ by iwi and hapū.
The celebration is underpinned by values of aroha (love), whakamaharatanga (remembrance), kotahitanga (unity), manaakitanga (caring), tohatoha (sharing), mana taiao (environmental awareness), hākari (feasting), wānanga (discussion), noho tahi (coming together), atawhaitanga (kindness), whakanui (celebrations) and tuakiritanga (identity).
The bill is only the fifth piece of legislation drafted in both te reo Māori and English.
Associate Minister of Arts, Culture and Heritage Kiritapu Allan - who championed the bill - said it was a historic moment, instituting the first national holiday specifically recognising and celebrating mātauranga Māori.
"Matariki is not about replacing an existing public holiday. Rather it provides us with a unique, new opportunity to embrace our distinctive national identity and helps to establish our place as a modern Pacific nation," Allan said.
"Matariki is a time of unity, renewal, celebration, and hope. With the challenges we have all faced in recent times, it allows us to come together with whānau and friends to pause, reflect and look optimistically to the future."
She said research showed many benefits to public holidays in general, including reducing employee stress, helping reduce burnout, and promote work-life balance; while it would also provide a much-needed mid-year boost to hospitality and tourism.
National MP Paul Goldsmith said the party was supportive of having a holiday which recognises and celebrates te ao Māori, but while he was looking forward to celebrating it the party believed Matariki should replace a previous public holiday.
"As if there is no cost, there is no consequences from this ... ultimately we as a country need to pay for it."
Labour's Grant Robertson said it was one of the measures the government was bringing in to better recognise "who we are in Aotearoa New Zealand today and who we can be".
Crown-Māori Relations Minister Kelvin Davis said members of the opposition who criticised the bill should listen to Māori and tikanga.
National's Simon O'Connor had raised the idea of instead of using the name of Matariki, using the Greek name Pleiades, or another name that was "more neutral". Davis said it showed National's contempt for anything Māori.
"They want to 'neutralise' our culture, our tikanga, our kaupapa ... that there goes to describe the attitude of the National Party."
Te Pāti Māori co-leader Rawiri Waititi said it had only taken 180-odd years to have an official day celebrating "the essence of what it is to be Māori".
"It is still a shameful stain on this country that Māori kaupapa or matauranga Māori is still to brown, or too native to acknowledge."
He said it was an annual reset, and offered a "huge window of opportunity to look at a more progressive, equitable and equal future for Aotearoa," saying it was time for a constitutional reset rooted in the Treaty of Waitangi.
