This study sheds new insight on how historically oppressed and marginalized actors are able to pursue environmental sustainability based on alternative worldviews (e.g., Indigenous worldviews) rather than succumbing to those dominant in the Western society, based on a study of the Syilx (“Okanagan”) people in British Columbia, Canada. We found that the Syilx people enacted the ethical practice of nʕawqnwixʷ (“the reciprocal gentle dropping of thoughts, like water, into everyone’s minds to address the issue at the centre of discussion and (...) to reach collective consensus for action”), anchored in the Syilx worldview, to reconstruct the relationships between humans and nature. Two overlapping processes are involved: developing foundational principles for human–nature relations and carrying out reconstruction work. Ongoing enactment of nʕawqnwixʷ practice provided community-based agency, enabling the Syilx people to shift the conversation around environmental sustainability. From this, we discuss the theoretical potential of community-based agency for the study of environmental sustainability, and the role of Indigenous worldviews for (re)imagining human-nature ethics (and reorienting the theoretical lens of human-animal or human-plant ethics form a firm-centric focus to a community-oriented lens), and important implications for practitioners and policymakers in the field of environmental sustainability. (shrink)