This quantitative-correlational study aimed to determine whether customer service significantly mediated the relationship of corporate social responsibility and business reputation. An adapted survey questionnaire which was validated by experts and pilot tested was used to gather pertinent data. A total of 382 purposively selected member-consumers of the electric cooperatives in Caraga Region were the respondents of the study. Mean, standard deviation, Pearson Product Moment Correlation, regression analysis and Medgraph were the statistical tools used. The findings of the study revealed that the levels of corporate social responsibility, business reputation and level of customer service were very high. Significant and positive correlations were obtained between corporate social responsibility and business reputation, corporate social responsibility and customer service and customer service and business reputation. Results also showed that corporate social responsibility and business reputation were partially mediated by customer service. Customer service is one of the aspects of corporate social responsibility which can influence business reputation.