Traditionally used within the context of hard military power in interstate relations, the concept of deterrence has been progressively extended to non-state actors and new issue areas. While scholarship on the social aspects of deterrence has expanded our understanding of this core international security practice, the focus of existing research has largely remained on physical security. This article argues that there is a phenomenon in international politics that can be called memory-political deterrence. Memory-political deterrence refers to the ways in which states seek to dissuade other political actors from taking actions that threaten the collective memory narratives that underpin the ontological security of the deterring actor. Memory-political deterrence works, for example, through political rhetoric, declarations, diplomatic insults, commemorative practices, and punitive memory laws. We illustrate the article’s arguments through empirical examples from Russia’s and China’s recent memory-political deterrence efforts toward Ukraine and Japan, respectively. In doing so, we elucidate the ways in which memory politics is intertwined with geopolitics, underpinning wider world-ordering aspirations.