Through qualitative, descriptive and exploratory research, including interviews and other qualitative data sources, this article addresses empirical and conceptual gaps in the existing literature on emotions in forming collective identity, social cohesion and resilience within contemporary (post-2000) transnational environmental activism in the (post) conflict Western Balkans. The research contributes to debates surrounding environmental activism and social movements and their role in conflict-affected societies. This article enhances understanding of how emotional contagion over shared environmental concerns facilitates cross-border solidarity, reconciliation and resilience in a (post) conflict society. Notably, contemporary transnational movements focused on preserving pristine rivers have maintained momentum for over a decade, successfully bridging political and ethnic divides. The article establishes that shared cultural narratives emphasising the neutrality of environmental causes, pride in natural heritage and emotions of grief and anger over ecological degradation, can effectively promote collective responses among historically hostile communities, positioning environmental activism as a means of dialogue, healing and cooperation. The article offers a new perspective on environmental activism, bridging historical divides, promoting long-term social stability and paving the way for sustainable development in conflict-affected areas.