Teachers' subjective well-being is closely linked to the advancement and effectiveness of digital teaching. Time is a fundamental resource for teachers adapting to the development of digital teaching and is also a potential factor influencing their subjective well-being in a digital context. Although time poverty is widespread among teachers, there is currently a lack of research on the relationship between time poverty and teachers' subjective well-being. This study, using a cross-sectional survey and based on theoretical models such as Job Demands-Resources (JD-R) model, explores the relationship between time poverty and teachers' subjective well-being, and examines the mediating role of emotional exhaustion and the moderating role of social support. A total of 525 Chinese primary and secondary school teachers participated in the study. The results indicate that: (1) Time poverty does not have a significant direct effect on teachers' subjective well-being; (2) Emotional exhaustion fully mediates the relationship between time poverty and teachers' subjective well-being; (3) Social support negatively moderates the relationship between time poverty and emotional exhaustion. The findings underscore the central role of emotional exhaustion in the process by which time poverty affects teachers' subjective well-being, as well as the protective role of social support. This study fills a gap in the research on teachers' subjective well-being and provides empirical evidence from the perspective of time poverty, contributing to the promotion of teacher well-being and the optimization of the digital teaching environment.