In this article we develop a geopolitical ecology of foreign conservation assistance. While the literature on the political nature of foreign assistance writ large highlights how geopolitical agendas are pursued through foreign assistance, we focus on how this geopolitics of foreign assistance articulates with biodiversity conservation concerns. We draw attention to how conservation donor agencies negotiate shifting geopolitical contexts in which the protection of biodiversity from the illegal wildlife trade (IWT) is increasingly framed in the language of national security concerns. We ask: Does framing IWT as a national security concern shape the allocation of foreign conservation assistance? What can answering this question tell us, both empirically and conceptually, about the geopolitical ecology of foreign conservation assistance specifically, and about the meaning of biodiversity conservation efforts to the state more broadly? We approach these questions by combining in-depth qualitative and quantitative analyses of the foreign conservation assistance provided by the US’ lead wildlife conservation agency, the United States Fish and Wildlife Service (USFWS). Between 2002 to the end of fiscal year 2018, the USFWS Division of International Affairs provided assistance to 4142 projects across 106 countries worth over USD $301 million. Our results show that an increasing portion of foreign assistance for biodiversity conservation is allocated to projects that have the specific objective of combating wildlife trafficking (CWT) at the expense of other conservation priorities. This transformation of what it means to fund conservation work overseas, we argue, lies at the heart of an emerging and intensifying geopolitical ecology of conservation, marked by increasing efforts to link the illicit harvesting and trafficking of wildlife with concerns about threats to national security. We conclude by discussing what a geopolitical ecology lens offers for understanding international assistance, biodiversity conservation, more traditional geopolitical concerns, and the intersections between them.