Purpose This study aimed to identify the mediating effects of positive psychological capital on the relationship between occupational stress and organizational commitment in physician assistant nurses. Methods The participants were 152 physician assistant nurses recruited from two university hospitals. Data was collected through a survey. The SPSS/WIN program (version 25.0) was used for the data analysis. Data was analyzed using descriptive stastics, t-test, ANOVA, Pearson’s correlation analysis, and hierarchical regression. Results There was a significant negative correlation organizational commitment and occupational stress (r=-.57, p<.001), and a positive correlation with positive psychological capital (r=.47, p<.001). There was a negative correlation (r=-.32, p<.001) between occupational stress and positive psychological capital. In addition, positive psychological capital had a partial mediating effect on the relationship between occupational stress and organizational commitment (β=.32, p<.001). Conclusion Positive psychological capital serves as a partial mediator in the relationship between occupational stress and organizational commitment among physician assistant nurses. The results of this study can be used reduce occupational stress and improve organizational commitment by improving the positive psychological capital of physician-assistant nurses.