Within the burgeoning doctoral mobility scholarship, inhabiting an entwined international and doctoral student status has been argued to render the PhD enterprise peculiarly challenging for candidates. Nonetheless, recognizing that this academic population has a relatively higher level of maturity and sophistication, research has increasingly turned attention to their agency exercised in navigating the international PhD experience. Notwithstanding the surge of research adopting this agential lens, a clear and integrated knowledge of what precisely constitutes agency has yet to surface. To address this concern, we systematically reviewed 28 papers wherein references to the agency of international doctoral students have been explicitly present. The results reveal that agency has more often appeared as an epiphenomenal phenomenon than being prioritized as a focal research object across the literature. For this reason, the characterization of agency as a static human property has been found to take dominance and evidence to the varying individual and structural influences over students' agentic actions are largely bereft of theoretical underpinnings. Furthermore, while enacting agency has been substantively cited to induce individuals' development and change, there are few testimonies to the difference it makes on social and cultural structures that have commonly transpired as constraints. Informed by the findings, we outline a research agenda serving to promote the central empirical investigation and the fluid conceptualization of student agency in the international academic mobility context.