The aim of this study is to analyse and compare how the rights of low-skilled labour migrants have been formed and developed in Japan and South Korea, from a discursive institutionalist perspective. Over the last two decades, interestingly, the two East Asian nation-states, although having similar policy legacies of East Asian welfare and immigration regimes (productivism and ethnic nationalism), have demonstrated different policy developments regarding the two groups of low-skilled labour migrants, resulting in different paths in terms of their rights – i.e., persistent ethnic differentiation in Japan and ethnically hierarchical inclusion in Korea. This article argues that the rationale behind the difference between Japan and Korea can be found in their different discursive interaction processes of policy legacies and alternative policy ideas (human rights and multiculturalism). That is to say, policy legacies have legitimised and strengthened the existing policy paradigms of low-skilled foreign-born populations – i.e., ethnic differentiation in Japan and differential exclusion in Korea, whereas alternative ideas have reinforced and/or challenged the paradigms, thereby engendering different approaches to the inclusion/exclusion of low-skilled labour migrants.