1.We show how the dire state of the Earth's rivers entangles intimately with ‘thingifying’ processes at the heart of colonial modernity. Known in many precolonial and Indigenous contexts as person-like kin, we describe how rivers the world over have been re-done primarily as thing – amoral, controllable, a potential commodity like anything else. 2.We develop and work with a provisory concept of kin as those constituents of environments that reciprocally nurture, and contribute to the substance of, one another’s life and well-being. 3.We show how kinship with rivers figures centrally in primarily Indigenous-led struggles in various regions of the globe for the recognition and enforcement of river personhood and rights. This is partly because people are motivated to fight passionately for their kin. 4.With some careful caveats, we argue that associating river kinship exclusively with Indigenous worlds undermines its potential for global impact. Thus, as an apposite case study, the latter part of the paper focuses on some of the social-ecological trends which we suggest are opening up the possibility for the re-establishment of ‘riverkinship’ in the United Kingdom. 5.We reflect on the potential for riverkinship to help cultivate political constellations fitting to the challenges of the Anthropocene