This article contributes to the theoretical understanding of institutions as fundamental in shaping the demand for migrant labour by investigating labour market regulation as possible explanation for cross-country differences in labour market segmentation and the presence of migrant workers. It compares the adult social care sector in England and the Netherlands with important cross-country differences in the reliance on migrant labour amid similar cost saving policies and marketization drives. The analysis draws on data collected between 2009 and 2019 and consisting of sectoral survey data, policy documents, interviews with relevant actors, and the observations of trade union and care workers’ meetings. The findings highlight the importance of path-dependent features of the national industrial relations systems in explaining observed differences but also how the specific nature of the regulatory outcomes depends on unions’ strategies and power.