Immigrant youth accumulate expansive linguistic, cultural, and experiential knowledge through their border‐crossing experiences. These transnational funds of knowledge accompany immigrant youth as they enter various literacy development contexts, including community‐based heritage language (HL) schools. This ethnographic case study focuses on a 15‐year‐old Korean American female student and the ways she sustains her HL by maintaining her transnational connections. This study also highlights how the focal youth passes down her multilingual and transnational expertise to younger generations by fostering the children's HL literacy and teaching them culture through her transnational experiences. The study demonstrates the importance of recognizing immigrant youth's transnational experiences as curricular resources and creating opportunities for them to mentor and teach young children as youth‐educators. Additionally, this study shows that youth should be involved in designing culturally sustaining HL curriculum to help support the HL and literacy learning of children and youth from immigrant families.