Teanau has over 20 years experience as an activist, an advocate, and organiser at local, national, and international levels.

He attributes his interest in political change to his mum (Ngāpuhi) and his grandfather (Atiu). After going to the Anti-Springbok tour protests with his mum in 1981, the idea of making things better stuck with him. After high school, he went to Auckland University and found himself learning about politics in Dr Ranginui Walker's class. The next year he enrolled in an environmental science paper taught by Jeanette Fitzsimons. He credits this for opening his eyes on issues around biodiversity and climate change along with being active in student politics.

Teanau describes himself as both tangata whenua and tagata moana and is the Greens First Pasifika MP. with Cook Islands and Māori heritage, being Cook Islands Māori (Atiu – Ngati Ingatu, Ngati Toki, Ngati Paerangi) and New Zealand Māori (Te Uriroroi, Ngāpuhi and Ngāi Takoto), and is a List MP based in Palmerston North.

In Pasifika communities, Teanau is known for his work in the education sector and climate change advocacy, while in Māori communities he is known for his indigenous rights activism. He has a particular interest in working at the intersection of indigenous rights and environmental issues, and has worked at the United Nations, amplifying the voices of remote indigenous communities on the frontlines of climate change and biodiversity loss..

Teanau sees the Greens as the Parliamentary wing of a wider Green movement acknowledging the privilege and opportunity to amplify the voices of communities that he is deeply committed to.

 "We follow in the path of all the environmental and social justice activists that have gone before us and make sure we do everything to look after the planet so that our mokopuna can thrive in the future".