In this article, we examine the potential of collaborative online international learning as a borderland third space for global citizenship education. Border thinking is used as a mode of critical questioning and reflection of ways of relating to the world, of feeling, acting, living and inhabiting the world that emanates from plural knowledges disrupting modernity and repositioning alternative knowledge traditions. After discussing the central concepts of collaborative online international learning and global citizenship education, and unpacking border thinking and third space as a lens, we provide four illustrative autoethnographic vignettes from which we then discuss collaborative online international learning and global citizenship education critically. We conclude that by bringing together students to engage in a collaborative learning task that they would be unable to complete on their own, participants have a personal and collective opportunity to appreciate each other's microsocial realities better. We argue that the potential for becoming in the collective borderlands of collaborative online international learning can deepen students' learning and understanding of global citizenship education as inclusive, decolonising, Indigenising, critical and transformative. However, collaborative online international learning for global citizenship education should not be deployed uncritically as an online pedagogy, assuming inclusivity. Rather, it can be a core component of holistic learning practice, if it is deliberately used as a borderland third space where valuable learning through reflection and openness to discomfort advances a global mindset.