Since the beginning of the 21st century, Romanian migrants have become one of the most significant national groups doing agricultural work in Spain, initially coming via a temporary migration program and later under several different modalities. However, despite their critical importance for the functioning of Europe’s largest agro-industry, the study of this long-term circular mobility is still underdeveloped in migration and agriculture literature. Thanks to extensive fieldwork carried out in the provinces of Huelva and Lleida in Spain and in the counties of Teleorman and Buzău in Romania, this paper has two main objectives: first, to identify some of the most common forms of mobility of these migrants and second, to discuss whether this industrial agriculture, hugely dependent on migrant work, is socially sustainable. The case of Romanian migrants in Spanish agriculture will serve to show how a critical sector for the EU and for the 2030 Agenda for Sustainable Development of the United Nations, operates on an unsustainable model based on precariousness and exploitation.