This paper introduces the concept of affective stakeholders, a mobilized form of affective publics whose engagement challenges core assumptions of stakeholder theory. Through a case study of Hawai‘i’s shark fishing policy, we trace how social media influencers recontextualized a government stakeholder engagement activity, transforming its purpose and catalyzing affect-laden processes that drove a wave of unintended participation. Most participants had no direct stake in the policy but were mobilized by narratives embedded with affect and misinformation. By co-opting government messaging, a small number of influencers leveraged social media affordances to activate affective publics who claimed stake in faraway decisions. This phenomenon was distributed and iterative, with no clearly responsible actor. We argue that affective stakeholders pose an emerging challenge to stakeholder theory and environmental governance, especially as participatory processes grow increasingly vulnerable to reinterpretation within volatile and affectively charged online networks.