For many governments, forming a shared national identity and uniting the public are among the major tasks for building a resilient nation. The population of multicultural children is increasing in South Korea due to globalisation. In the face of such social change, the Korean government has implemented policies and programmes to support these children. The purpose of these policies and programmes is to help multicultural children develop a national identity as Koreans and thereby assimilate them into the Korean culture and ensure social integration. This study examined how government policies affect the national identity formation of multicultural youth. It found that government programmes are effective in developing these young people's national identity as Koreans, and the result is supported by robustness checks. Furthermore, the effects were dependent on the nationalities of the multicultural youth's mothers, which suggests that the government needs to consider the heterogeneous nature of multicultural families when constructing policies.