Chloe Swarbrick, former Auckland mayoral candidate, is joining the Greens and intends to run in next year's general election.
She posted the announcement on Twitter and Facebook on Friday, where she built a following during her unsuccessful mayoral campaign.
Ms Swarbrick told Newshub that she chose to go with the Greens because she believes "in their values, processes, and policy" and their "commitment to ecological wisdom, social responsibility, appropriate decision making and non-violence".
Ms Swarbrick says in the video people across the world are "dissatisfied with the establishment and status quo" and she wants to start "a new conversation about the future that we, as New Zealanders, want for our country".
The 22-year-old says there is "a tide for change" and a desire for "progressive, inclusive, compassionate and empathetic politics".
Greens co-leader Metiria Turei says the party is excited Ms Swarbrick has joined.
"The Green Party has always encouraged young people to be part of our political process. We need young people to be part of politics now more than ever.
"Chloe ran a successful local body campaign in Auckland, and obviously she'll be bringing those skills and that experience to the Green Party, which is great."
The party's candidate application process is open until the end of November, and party members will decide the list ranking for candidates next year.
"We've had some talented people put their names forward, including Chloe."