This article examines how the far-right political party Alternative für Deutschland (AfD) mobilizes population replacement conspiracy theories, particularly the concept of Umvolkung, as a mode of political propaganda. While the genealogy of Umvolkung harks back to the Weimar Republic, and it is also tied to the racial and demographic engineering of the Nazi era, it has re-emerged in contemporary far-right discourse as a conspiracy theory of population replacement. In this article, I argue that the AfD’s deployment of population replacement conspiracy theories operates as biopolitical technologies seeking to legitimize exclusionary projects such as the “Remigration” program. Ultimately, I contend, population replacement conspiracy theories promote a biopolitical vision of protecting the national racially characterized social body from the existential threat of replacement through tightening border regimes, reconceptualizing concepts of citizenship and naturalization, and entertaining the political death of those racially characterized as non-Germans by means of exclusion-remigration imaginaries.