Engineering vehicle drivers are exposed to high-workload and high-risk operating environments for long periods. Unsafe driving behavior is regarded as an important contributor to traffic accidents. To investigate the effects of psychological factors on unsafe driving behavior among engineering vehicle drivers, perceived behavioral control was further divided into two psychological dimensions, namely perceived risk control and perceived emotion regulation, based on the traditional Theory of Planned Behavior (TPB). An improved TPB-based structural equation model incorporating multiple psychological factors was developed. Valid questionnaire data were collected from 1,387 engineering vehicle drivers and were empirically analyzed. The results show that, compared with the traditional TPB model, the explanatory power of the improved model for unsafe driving intention is increased by approximately 15.4%, while that for unsafe driving behavior is increased by approximately 1.1%. Unsafe driving intention is significantly and positively affected by negative driving attitude. It is significantly and negatively affected by perceived risk control and perceived emotion regulation. Actual unsafe driving behavior is significantly and positively predicted by unsafe driving intention. The multi-group analysis further shows that the effects of psychological factors on unsafe driving intention vary across drivers with different ages, driving experience, average daily driving duration, and accident experience. Perceived risk control and emotion regulation are identified as important psychological mechanisms for inhibiting unsafe driving behavior. The internal psychological-behavioral mechanism of engineering vehicle drivers is further clarified. The findings provide theoretical support and empirical evidence for improving engineering transportation safety through psychological intervention and emotion management.