Student mobility is becoming a prominent phenomenon of tertiary education in the twenty-first century. Internationally mobile students' lived experiences are intimately linked to their potential to exercise agency in transnational mobility. However, the notion of agency within the context of student mobility has not been the explicit focus of theoretical and empirical investigation. This article examines how international student agency is affecting and is affected by their experiences in transnational mobility. This process is conceptualized as "agency in mobility" in this article. Based on theoretical discussions and an empirical study that draws on interviews with 105 international students, this article shows that "agency in mobility" underscores not only the response to a temporal particular need but importantly produces spaces in which international students can potentially transform their present, their future beings and the communities with which they interact. Employing agency theory and positioning theory as conceptual frameworks, the research suggests four primary forms of "agency in mobility": "agency for becoming," "needs-response agency," "agency as struggle and resistance" and "collective agency for contestation."