Marama Davidson says it is the greatest honour of her life to be elected as the new female co-leader of the Green Party.
Ms Davidson won the leadership contest with 110 delegate votes to fellow MP Julie Anne Genter's 34 votes.
In her acceptance speech in Auckland this morning, Ms Davidson said her number one goal would be to ensure the Greens don't lose support while they are part of the Labour-led Government.
"History shows that smaller parties struggle to retain their support in coalition governments, lose influence and can sometimes fracture," she said.
"We can't clean our rivers, save our native species, lift our families out of poverty, build warm safe houses and new public transport if our party isn't united and positive, governing and campaigning for change."
The Green Party needs to grow its vote - and win back the support of those voters who turned their back on the party in 2017 - and ensure in 2020 it returns to Parliament with more MPs and more influence, Ms Davidson said.
Without ministerial responsibilities, Ms Davidson said she can can focus on the party and ensure the full delivery of their confidence and supply agreement while maintaining unity.
"With one leader as a Minister and one not we are able to avoid the pitfalls other parties entering Government have experienced who have seen their support fall."
The Green Party needed to work on representing a broad cross-section of New Zealanders, as well as regaining the trust and support of those who didn't vote for the party in 2017, she said.
"We need to be present in multicultural, Māori and Pasifika communities, in provincial and rural communities, and in the suburbs, with women, young people and workers."
Ms Davidson also referred to her upbringing, having grown up in south Auckland and the rural communities of Hokianga and the East Coast in the 1980s.
"I witnessed first-hand the devastating effect the introduction of that [broken] economic model had on communities and what followed; intergenerational poverty and the tragic, direct legacy of suffering and suicide in our regions and urban centres," she said.
"We are still feeling that impact, here, now. Parliament needs to turn our faces to the streets, to communities right up and down this country, and understand the hardship and struggle that so many of our people are facing."
Ms Davidson also paid tribute to her fellow leadership contender, Ms Genter, describing her as one of the sharpest political minds in Parliament.
After eight months leading the party alone, James Shaw said he was looking forward to having Ms Davidson as his co-leader.
He said Ms Davidson "lit a wildfire through the party" during her leadership campaign.
Now was the time for the party to unite and get on with the job of being part of Government, Mr Shaw said.
In a statement Prime Minister Jacinda Ardern offered her congratulations to Ms Davidson and said she was looking forward to working with her.
"This Government was formed around a consensus to make progress on the issues that matter most to New Zealand including an economy that delivers for everybody, a much stronger focus on the environment and a commitment to invest in our people," Ms Ardern said.
"I am sure our work will be strengthened with the addition of Marama Davidson helping to leading this important work alongside me, Deputy Prime Minister Winston Peters, and Green Co-leader James Shaw."
The Green Party's constitution dictates that it must have both a male and female co-leader.
The female position became vacant after Metiria Turei resigned in the run up to last year's General Election after revealing she had committed benefit fraud.
Ms Davidson, 44, has been an MP since 2015. She was already number two on the party's list. She doesn't hold any ministerial roles in the Labour-led Government.
She is of Ngāti Porou, Te Rarawa, and Ngāpuhi descent. She's the daughter of the actor Rawiri Paratene.
She is a graduate of the University of Auckland, and of Te Whare Wanaga o Awauiarangi, worked for 10 years at the Human Rights Commission, and was chief panelist for the Glenn Inquiry into Domestic Violence and Child Abuse.
She lives in Manurewa and has six tamariki.