This study examines whether health insurance enhances the subjective well-being (SWB) of China’s rural-to-urban migrant workers. Despite their key contributions to economic development, these workers remain marginalized in the social security system. As a crucial component of social protection, health insurance may improve healthcare access and financial security, thus boosting well-being. Using data from the 2018 China Family Panel Studies (CFPS) and applying an ordered logit model, this paper explores the effects of health insurance participation. The findings suggest that both coverage and participation depth significantly improve migrant workers’ SWB. Moreover, the effects vary across gender, education, and region. The study concludes with policy recommendations for government agencies, insurers, and migrant workers to enhance insurance effectiveness and support the well-being of this vulnerable population.