The optimization of human resources is critical for organizational success, particularly in competitive sectors like banking. This study aimed to design an effective performance evaluation system for employees of Saman Bank’s Grade 2 branches in Mazandaran Province, Iran, during 2020–2021. Employing a descriptive survey method, the research involved 40 employees and utilized literature reviews, expert opinions, questionnaires, and interviews to identify key performance indicators (KPIs), determine their weights, and develop an executable evaluation framework. Fourteen KPIs were selected, with “work conscientiousness” and “work quantity” ranked as the most significant. The proposed system includes a three-month evaluation cycle, clear guidelines for evaluators, and structured feedback mechanisms to enhance employee performance. Results indicate that a well-implemented evaluation system can improve organizational efficiency, employee motivation, and alignment with strategic goals. The study offers practical recommendations for Saman Bank to refine its performance evaluation processes, contributing to human resource development and organizational competitiveness. This research underscores the importance of systematic, transparent, and objective performance evaluations in fostering employee growth and organizational success.