Abstract Infectious diseases pose significant challenges to public health, leading to illness and even death. Vaccinations are vital for protecting society, yet beliefs in conspiracy theories related to infectious diseases increase vaccine hesitancy. This paper delves into vaccination decisions in the context of COVID‐19, which continues to strain the health care system. While past research focuses on countering conspiratorial beliefs with cognitive persuasion interventions, we propose a social intervention as an alternative. Our novel intervention seeks to mitigate the effects of conspiratorial beliefs by fostering individuals' interdependent self‐construal – viewing oneself in the context of social relationships. Interdependent self‐construal was operationalized in multiple ways (measured in Studies 1, 2 and 3; manipulated to test causality in Studies 4 and 5). Conspiratorial beliefs were also manipulated in Study 5. The results show that the association between conspiratorial beliefs and vaccine hesitancy is weakened among individuals whose interdependent self‐construal is more accessible. Moreover, this effect was mediated by prosocial motivation. We discuss the implications of our findings for developing and communicating health policies and propose potential contexts where this intervention may be relevant, thereby providing valuable insights into enhancing societal well‐being in the face of conspiratorial beliefs.