Serbian migrant workers have played a prominent role in the expansion of the Slovak automotive sector in the 2016-2019 period, but became a less dominant migrant group by 2023. Analysing statistical data on Serbian labour migrants in Slovakia, migrant workers in Slovak automotive companies, as well as secondary sources and interviews, in this article we shed light on the determinants of temporary or circular labour migration and its interrelation with a sectoral and company-based labour regime. Our assessment incorporates factors such as the needs of employers, sector-specific considerations, the role of intermediaries and the motivations of migrant workers. We show that migrant workers’ labour was a key factor in subsidiaries of global automotive companies' strategy to expand production and employment, and simultaneously cut costs, putting constant pressure on working conditions and wages. Thus we found that employers - user companies were consciously shaping such a migrant labour based regime. Unions could only modestly remedy the highly flexible arrangement. Finally, our exercise shows that Serbian workers integrated in a highly precarious manner in Slovak automotives, which corresponds to declining migration trends from Serbia since 2019.