The objective of this study was to examine the effect of five dimensions of organizational citizenship behavior (OCB) - altruism, conscientiousness, civic virtue, sportsmanship, and courtesy - on employee performance at the Commercial Bank of Ethiopia (CBE), Bahir Dar city. An explanatory design was used and questionnaires were distributed randomly to 224 employees, with 218 valid responses used in the analysis. Descriptive statistics and a multivariate regression model using SPSS version 20 were used to investigate each dimensions of OCB. Correlation analysis revealed strong positive relationships between conscientiousness, courtesy, altruism, and employee performance, while civic virtue and sportsmanship showed moderate positive correlations. Regression analysis further revealed that conscientiousness, civic virtue, and sportsmanship were found to be significant explanatory variables of employee performance, with conscientiousness being the strongest explanatory variable. Both conscientiousness and civic virtue had significant positive effect on employee performance. Altruism and courtesy did not show significant relationships with employee performance. The findings suggest that cultivating organizational citizenship behaviors, particularly conscientiousness and civic virtue, may contribute to enhanced employee performance of CBE employees in Bahir Dar city.