Nursing performance can be an evaluation indicator of hospitals. Therefore, improving it positively affects the development of nurses, patients, guardians, hospitals, and society. This descriptive correlational study was conducted to provide basic data necessary to improve nurses’ work performance by examining the effects of nurses’ grit on nursing job performance and mediating effects of job satisfaction and organizational commitment. The study participants were 186 nurses working at a university hospital in G province, Korea, with working experience of more than six months. Data analysis was performed using IBM SPSS Windows program version 21.0, descriptive statistics, Pearson’s correlation, and multiple linear regression according to the purpose of the analysis in this study. In addition, PROCESS macro was used to test the mediating effect. We examined the mediating effect of job satisfaction and organizational commitment in the relationship between nurses’ grit and nursing job performance. We found that the indirect effect of job satisfaction was significant in that nurses’ grit influenced nursing job performance (B = 0.11, CI = 0.05–0.21). The indirect effect of organizational commitment was also significant in influencing nurses’ grit on nursing job performance (B = 0.12, CI = 0.04–0.22). These findings contribute to the improvement of nurses’ nursing performance. When grit improves, efforts are made to achieve job satisfaction and maintain organizational commitment through focusing on work with steady effort and interest in the goal. Based on this study, enhancing the grit that predicts individual nurses’ achievement can enhance nursing job performance. Nevertheless, interventions to improve job satisfaction and organizational commitment should be developed and implemented.