According to the OECD, New Zealand is among the few countries where the performance gap between immigrant and non-immigrant students in the Programme for International Student Assessment (PISA) is minimal, reflecting the effectiveness of its inclusive education system. Grounded in the bicultural framework established by the Treaty of Waitangi (New Zealand's founding treaty) and actively embracing multiculturalism in response to increased migration from the Pacific and Asia, New Zealand embeds multicultural values across curriculum, pedagogy, and community engagement. Schools such as Papakowhai, Rangikura, and Wairakei illustrate how culturally sustaining practices validate students’ identities, draw on community knowledge, and strengthen equity in learning. Diversity is treated not as a challenge to be managed but as a resource that enriches educational experiences for all students, fostering both academic achievement and social inclusion. In contrast, South Korea, long perceived as ethnically homogeneous, continues to frame multicultural education largely through an assimilationist lens, positioning multicultural families as requiring support rather than as contributors to knowledge and culture. As a result, policies risk reinforcing social hierarchies and marginalisation, limiting the potential benefits of diversity in education. This paper argues that South Korea can draw meaningful lessons from New Zealand's approach by reframing multiculturalism as a central educational principle, recognising diversity as an asset, and embedding it systematically within curriculum design, teacher education, and community partnerships. Doing so would enable the development of a more equitable, inclusive, and justice-oriented education system that equips all students—majority and minority alike—to thrive in an increasingly pluralistic and interconnected society.