This study aims to investigate the role of moral courage in the relationship between professional identity and auditors’ professional skepticism. Given its nature, this research is classified as applied research, and in terms of methodology, it falls within the category of descriptive-survey studies. The statistical population consists of 1,879 certified auditors actively employed in audit firms that are members of the Iranian Association of Certified Public Accountants. Using Cochran’s formula, a sample size of 319 auditors was determined and examined. In this study, auditors’ professional skepticism served as the dependent variable, professional identity as the independent variable, and moral courage as the mediating variable. To measure professional identity, the Professional and Organizational Identity questionnaire developed by Brubaker et al. (2018) and the Ethical Identity scale by Aramini and King Jiang (2021) were used. Moral courage was assessed using Johnson’s (2021) standardized questionnaire, and Hart’s (2013) questionnaire was employed to measure professional skepticism. Responses were scored on a five-point Likert scale. Construct validity was used to confirm the scale’s validity. Reliability was assessed using Cronbach’s alpha and composite reliability, both indicating acceptable levels of reliability. Structural equation modeling was employed to examine the relationships among variables, utilizing SPSS version 25 and Smart PLS version 4 software. The results of hypothesis testing indicate that auditors’ professional identity significantly influences both their professional skepticism and their moral courage. Furthermore, auditors’ moral courage significantly affects their professional skepticism. Additionally, moral courage plays a mediating role in the relationship between professional identity and professional skepticism.