This study examines Korean language teachers’ perspectives and experiences with student diversity in Canadian Korean language classrooms, focusing on how these beliefs inform pedagogical practice. As culturally and linguistically diverse learners have become common across Canadian schools, heterogeneous student groups in Korean language programs are now typical. However, limited research has explored how teachers conceptualize diversity within Korean language education or how such understandings shape instruction. Drawing on semi-structured interviews with four teachers working in varied educational contexts, the study investigates how teachers define diversity, perceive its relevance, and translate these perceptions into pedagogical decisions. Findings indicate that all participating teachers have witnessed a substantial rise in classroom diversity in recent years. Overall, they expressed positive attitudes toward this shift, recognizing its pedagogical benefits while also acknowledging the challenges associated with meeting increasingly complex learner needs. Teachers attributed this demographic change largely to the global expansion of Korean popular culture—driven by the Korean Wave—and to the broader elevation of Korea’s international status. The analysis further demonstrates that teachers’ awareness of learners’ ethnic, linguistic, and cultural backgrounds enabled the creation of supportive and responsive learning environments in which instruction could be adapted to accommodate diverse forms of knowledge and experience. Taken together, these findings underscore the critical role of teachers’ attitudes toward diversity in shaping equitable and meaningful Korean language learning experiences. The study highlights the need for continued professional development focused on diversity-responsive pedagogy to better support the evolving learner populations in Korean language classrooms.