Agrarian industries in rural areas are increasingly relying on seasonal migrant workers, who arrive in transnationally organised settings. This paper focuses on the concept of transnational simultaneity in order to further analyse the dynamics that are sustaining low-wage, seasonal labour migration in transnational social fields. It is suggested that the concepts of seasonal livelihood diversification and biographical simultaneity contribute to explain this process, which is highlighted in relation to the empirical case of Thai wild berry pickers in Sweden. The ability of the workers to co-arrange life in the homeland with work overseas, together with a firmly institutionalised, transnational social network, lay the ground for the Thai-Swedish migration process. It is characterised by high circularity and frequency among the migrant workers, who oscillate on a seasonal basis between multi-sited work places, despite relatively low economic return. It is argued that simultaneity within the transnational social field, which is embedded in seasonal livelihood diversification and prospects of improved futures for their children, lowers the threshold for accepting exploitative work conditions, thus paving the way for precarious migrant work.