Across multiple jurisdictions, Indigenous and ethnic communities have sought recognition and protection of the legal rights of rivers as part of broader activist agendas seeking greater legal and political control over their lands and resources. Yet the legal scholarship tracing these cases of ‘river rights’ has often ignored the role of activism in driving and shaping river rights frameworks, as well as the broader implications of these frameworks for community activist agendas. In this article, we examine two legal cases in which Indigenous and Afrodescendent peoples have used legal and extralegal strategies to secure protection for the rights of rivers: for the Piatúa River in Ecuador and the Atrato River in Colombia. In both cases, we find that communities are strategically leveraging river rights frameworks, alongside constitutional and human rights protections, to assert and enhance their territorial autonomy. While the project of recuperating territorial autonomy is incomplete in both cases, our comparative analysis confirms that these cases should be seen as incremental steps in a broader project of transforming community relationships with government institutions, local authorities, and the courts, enabling more pluralist territorial governance to emerge over time.