Merely juxtaposing the accelerating number of undocumented migrant children and their distinctive struggles is an inadequate approach to educational scholarship of early childhood teachers working with/for this child population. In this article, we zoom in on teachers at St. Mary's Preschool, who serve large numbers of migrant and undocumented children in South Korea, and explore their pedagogical caring practices in and outside of the classroom for these children and their families. The findings of this study demonstrate how preschool can become a site for what we term culturally, linguistically, and legally relevant caring for undocumented migrant children. The key tenets proposed include: (1) promoting diverse, inclusive, and culturally and linguistically relevant schooling; (2) attending to the legal reality of students' precarious legal status to provide a rich and safe learning environment; and (3) establishing reciprocity in relationship and knowledge-making/sharing. The study offers several implications for research and teacher education in the field of early childhood education by presenting a conceptual and empirical snapshot of how to better serve the growing numbers of young migrant and undocumented children and their families in South Korea and worldwide.