China was once called the world's factory. Chinese workers had long weekly working hours. However, the empirical results of the relationship between overtime work and workers' health are mixed and remain inconclusive. This study aimed to investigate how overtime work influenced workers' physical and mental health and the role of lifestyles, social support, and work value awareness. Data from the China Labor-force Dynamics Survey 2016 (N = 14,205) was used. The instrumental variable approach was employed to overcome the endogeneity problem between overtime work and workers' health. The bootstrapping method was conducted to elicit the role of lifestyles, social support, and work value awareness. The results indicated that overtime work significantly and negatively influenced Chinese workers' physical and mental health. The results of the bootstrapping suggested that workers' social support and work value awareness partially mediated the relationship between overtime work and their physical and mental health. However, the mediating role of lifestyles was insignificant. Through using big data with national representativeness, this study suggests that overtime work negatively influences Chinese workers' physical and mental health. Our findings provide policy implications for improving workers' health rights and well-being in emerging economies.