Charles is a prominent Māori scholar of Indigenous knowledge, iwi histories and traditions as a teacher, researcher and composer. Previously he was the director of Ngā Manu Atarau, Te Papa Museum of New Zealand, Professor of Indigenous Development, University of Auckland, Director of Ngā Pae o te Māramatanga, and Director of Graduate Studies and Research,Te Wānanga-o-Raukawa, Ōtaki.