Purpose This study aimed to investigate the effects of job characteristics and professional self-concept on competency in forensic nursing among operating room nurses at university hospitals. Methods: Data were collected from 164 operating room nurses employed at university hospitals. The collected data were analyzed in SPSS 23.0, using the mean, standard deviation, independent t-test, one-way analysis of variance, Scheffé post-hoc test, Pearson correlation coefficients, and multiple regression analysis. Results: Professional self-concept showed a statistically significant positive correlation with forensic nursing competency (r=.60, p<.001). The following factors significantly influenced forensic nursing competency among operating room nurses: professional self-concept (β=.69, p<.001), total career lengths of <5 years (β=.21, p=.006) and 5-9 years (β=.20, p=.011), and job characteristics (β=.19, p=.007). A three-step regression model was statistically significant (F=29.74, p<.001) and the total explanatory power of the regression model was 41.4%. Conclusion: This study identified that professional self-concept, total career years, and job characteristics as the most significant factors influencing operating room nurses' forensic nursing competency. Therefore, it will be necessary to develop educational programs to improve professional self-concept and job characteristics.