Ethical decision-making is a fundamental element in maintaining professional credibility and strengthening public trust in the auditing profession. Logical reasoning enables auditors to objectively analyze complex ethical issues and propose solutions consistent with professional moral principles. However, psychological pressures arising from heavy workloads, tight deadlines, and organizational conflicts may negatively affect logical reasoning and reduce the quality of ethical decisions. Therefore, psychological stress can act as a moderating variable influencing the relationship between logical reasoning and ethical decision-making. This study aimed to examine the effect of logical reasoning on auditors’ ethical decision-making and the moderating role of psychological stress. The statistical population included all auditors working in the city of Yazd, whose exact number was unknown; thus, based on Morgan’s table for infinite populations, a sample size of 384 individuals was determined, and participants were selected through convenience sampling. Data were collected using a questionnaire and analyzed using SPSS 24 and SmartPLS 3 software through the structural equation modeling approach. The findings revealed a positive and significant relationship between auditors’ logical reasoning and their ethical decision-making, while psychological stress weakened this relationship. In other words, increased stress can reduce auditors’ ability to apply logical thinking when facing ethical dilemmas. These results enrich the related literature by highlighting the importance of environmental factors such as psychological stress and provide a basis for developing educational and managerial programs aimed at enhancing auditors’ logical reasoning and stress-management skills.