The agency of international students has long been neglected and undertheorised, though recent literature indicates that this has started to change. This paper systematically reviews 51 studies that address student agency in international higher education. Focusing on research published in the last two decades (2000-2020), the review draws on studies that foreground student voices, or international students' perspectives, rather than the perspectives of teachers, administrators or policymakers. A detailed discussion of how international student agency is positioned in the literature found that agency appears as either: a research object, as part of a theoretical or conceptual framework, or an emergent finding. Furthermore, our analysis suggests that the term "agency" is often used as a buzzword rather than as a fleshed-out concept. Thus, drawing on this initial analysis, the review synthesises varying but overlapping conceptualisations of international student agency in the literature into an integrative framework. Implications for future research are drawn, based on our findings about the understudied populations and methodological limitations in the literature.