Objectives: To explore the relationship between depressive symptoms, fatigue and psychological flexibility, as well as their interactions on depression in Chinese nurses. Material and Methods: Using convenience sampling, a cross-sectional survey of 796 nurses in municipal hospitals of Zhengzhou, Henan Province, China, was conducted. The questionnaires of Work-related Acceptance and Action Questionnaire, Center for Epidemiological Studies Depression Scale and Fatigue Assessment Instrument were used. Hierarchical regression and bootstrap methods were used to examine the mediating effect of psychological flexibility between fatigue and depression. Results: More than 51.8% of the nurses were at risk of depression and 62.3% were at risk of fatigue. There was a significantly positive and moderate correlation between depression and fatigue severity, situation specificity, and consequences (r = 0.43, r = 0.24 and r = 0.31, respectively, p < 0.01). Depression was negatively correlated with psychological flexibility (r = –0.28, p < 0.01). Psychological flexibility had a negative impact on depression with the explained variance increased by 4.2% (β = –0.211, p < 0.001). The bootstrap method showed that the mediating effect of psychological flexibility accounting for 8.5% and 12.3% on fatigue and depressive symptoms, respectively. Conclusions: Psychological flexibility plays a partial mediating role between the fatigue severity, consequences of fatigue and depressive symptoms of nurses. Hospital managers should improve medical staff work acceptance to alleviate their depressive symptoms. Int J Occup Med Environ Health. 2023;36(4):563–74