The main purpose of the study was to investigate the effect of organizational citizenship behavior on employees’ performance and the major focus of the study was to see the effects of the five dimensions of OCB namely altruism, conscientiousness, civic virtue, sportsmanship and courtesy on employees’ performance in CBE, Bahir Dar City Branches. To achieve the above research objective, the researcher employed quantitative research approach and cross-sectional research design and the target population comprised of 563 employees and using Yemane formula, the researcher determined the sample size of 234 respondents. Furthermore, the researcher used stratified sampling techniques and selected respondents of the study using random sampling particularly the lottery method. For the purpose of the study, primary data collected through standardized questionnaires. For analyzing the collected data, the researcher used descriptive statistics to assess the status of OCB and employees’ performance; Pearson correlation to see the relationship between OCB and employees’ performance, and regression analysis to examine the effect of OCB on employees’ performance. Moreover, based on the multiple regression results, each hypothesis tested and the result shows all the above five dimensions of CBE had a significant positive effect on employees’ performance in CBE, Bahir Dar City Branches. To sum up, for the improvement of their employees’ performance, it is advisable for managers or management to consider the encouragement and promotion of all the five dimensions of OCB in CBE, Bahir Dar City Branches.