"Nancy brings a wealth of iwi and central government experience to the kaihautū role," Albert said.
"She has always been committed to the health and wellbeing of the Awa and our people and she has a lot to offer the trust, our staff and Whanganui hapū."
Tuaine has been leading iwi initiatives in governance roles for Ngā Tāngata Tiaki o Whanganui, Te Whawhaki Trust and Awa FM in recent years.
"I am excited to drive us into this new phase of our development for our people and our Awa and to carry on the important legacy that has been handed down to us," she said.
"I get really passionate about the vision of our people, and I just want to get stuck in and make it happen."
In 2014, the Whanganui River was legally recognised as Te Awa Tupua, a living and indivisible whole from the mountains to the sea, including all its physical and metaphysical elements.
Ngā Tāngata Tiaki o Whanganui Trust is the post-settlement governance entity of Whanganui iwi for the purposes of the Whanganui River settlement.
Albert said Tuaine had stepped down from her governance positions with the trust.
"While we are sorry to lose Nancy as a trustee, we are excited for the contribution she will make as kaihautū."
Tuaine commenced her work as kaihautū on Monday, May 31.