Drawing on three cases of long-term Indigenous–settler alliances in Canada, this research investigates the roles and contributions of settlers towards decolonization. As a multidisciplinary team of Indigenous and non-Indigenous scholars, our research goal has been to understand how such alliances endure and change over time, and how they negotiate power dynamics, tensions and changes, within a settler colonial context. Taking a comparative case study approach, and analysing interviews, sharing circles and archival documents, we focus here on the lessons that alliance participants have learned from their activist experiences about settler roles and responsibilities. The three cases include (1) The Right to Belong: Indigenous women’s organizing and the struggle to eliminate sex discrimination in the Indian Act; (2) Shoal Lake 40 First Nation’s Freedom Road campaign to end a century of state-imposed geographic isolation and to secure access to safe drinking water; and (3) the alliance-building and solidarity activism of Canadian ecumenical social justice coalitions now under the umbrella of KAIROS Canada. While none of these campaigns alone equates to decolonization in the sense of land return and Indigenous sovereignty, each has helped create the conditions, relationships and transformations in settler consciousness that may provide the ground for decolonization. Taken together, the three case studies illustrate the contingent environments in which alliances are forged and the ways in which settlers take up particular responsibilities based on Indigenous-defined goals.