With the growing population of Koryeoin in Korea, research on this ethnic group’s international migration has also increased thus far. However, a majority of the studies have focused on adult Koryeoins, while little attention has been paid to young children, who are possibly experiencing tremendous cultural and linguistic challenges through involuntary migration. This study thus aims to investigate Koryeoin children’s ethnic identity and peer relations specifically focusing on their daily life in order to understand how their perceptions of self and socializing with peers are interrelated. Adopting an ethnographic-case study method, the researchers conducted the study in an elementary school located in Chungnam, which was one of the most densely populated areas of Koryeoin. The student participants were nine elementary school students aged between 11 and 15, and data was collected mainly through prolonged observations and semi-structured in-depth interviews of individual students. The study found that individual Koryeoin children tended to form idiosyncratic, multi-layered identities depending on the factors such as language proficiency, experiences of discrimination, and emotional ties with others. In terms of socializing, Koryeoin children formed relationships with Koryeoin peers for emotional solidarity and adaptation to Korea at the beginning of the migration; while they formed relationships with Korean peers to obtain useful information or to explore their own ethnic identity. Highlighting the Koryeoin children’s multilingual ability and resilience, this study suggests that Korean schools and society should provide proper and systematic support for this group of students.