The paper explores the transformation of environmental activist John Sinclair, OA, from a conservative member of the Country Party, through a position of cautious conservationism, to preeminence as a leading environmentalist with some very significant achievements. This paper aims to show some correlations between his work and ideas and major strands of environmental education research. His allegiance to K’gari (Fraser Island) and the way in which he was able to learn from the traditional custodians, the Butchulla people, and other leading environmentalists is described in this paper through his own memoir writing and the viewpoints of informants interviewed by the author. John Sinclair’s profound connection with K’gari, how it was formed and sustained, and its historical and environmental consequences make a remarkable story of a modern citizen turned activist. The development of John Sinclair’s ideas and practice show interesting parallels with the development of both environmental activism and environmental education in Australia. The story has importance in a range of areas connected with environmental stewardship and environmental education.