This paper examines an atypical south-north labour migration that emerged in the post-socialist international migration system: China-to-South Korea ethnic labour migration. Over the past decade, South Korea has experienced an unprecedented increase in the arrival of foreign labour. The majority of workers come from the People's Republic of China. Based on a contextual multivariate analysis of primary survey data on 525 predominantly undocumented Korean Chinese labour migrants in Seoul, this study reveals the underexplored economic dimension of ethnic migration in Northeast Asia. Empirical findings on this source of migrant labour in South Korea demonstrate that the China-to-South Korea ethnic population movement is an important yet an unknown dimension of the post-socialist global migration regime that is marked by the New Economics of international labour migration. The study suggests that ethnic migration from a socialist transition economy to a capital-rich economy linked through ancestral connections must be reconsidered in the context of the changing global migration and demographic landscapes, rather than the ethno-nationally romanticised view of the return of diaspora.