Born Te Kumeroa Ngoingoi Ngāwai, Ngoi Pēwhairangi was of Ngāti Porou and Ngāti Koi (Hauraki) descent. She was a prominent teacher of, and advocate for, Māori language and culture. She is well known as a composer of the song Poi E, sung entirely in the Māori language and featured a blend of Māori cultural practices in the accompanying music video. The song reached No. 1 in Aotearoa (New Zealand) in 1983 and in each of the following three decades. She also composed ‘Whakarongo’, a waiata urging the use of, love for and promotion of te reo Māori sometimes called the ‘anthem of the Māori language’. She was an advisor to the National Council on Adult Education and a promoter of Māori crafts, especially weaving. With Kāterina Mataira, she was a founder of the Te Ataarangi method of teaching and learning te reo Maori. In the 1970's Pēwhairangi was asked to assist in implementing the Tū Tangata programme, which focused on rescuing alienated urban Māori youth and connecting them to their iwi. Te Tai writes, "Ngoi Pēwhairangi saw te reo Māori as more than a language. It was a defining point of Māori identity."