Many organizations have adopted and implemented enterprise wide information systems that can be summarized in the term Enterprise Resource Planning (ERP) systems. Implementation of ERP systems within organizations plays critical a role in finance, human resource, supply chain and project management functions because it provides a platform for enhanced efficiency and effectiveness in organization’s productivity. However, ERP implementation is complex, costly and dogged by challenges. The general objective of this study was to assess the enterprise resource planning software (ERPs) adoption and implementation by major supermarket stores in Nairobi County. The specific objectives of the study were to; determine the ERP modules adopted and establish the effects of adoption of ERPs on performance of major supermarket stores in Nairobi County. The anticipation was that findings of this study would contribute towards ERPs implementation decisions. This study employed a quantitative research design to obtain an understanding of the extent to which the ERP modules adopted by major supermarket stores in Nairobi County impact on performance of the firms under study. The target population of this study included managers from the Information communication and Technology department, supply chain department, finance department and Human resource department and other knowledgeable staff in major supermarket stores in Nairobi County. A sample size of 30 respondents was selected using purposive sampling technique. Questionnaires were used for data collection and analyzed using quantitative analysis approach that included regression and correlation statistics with the aid of the Statistical Package for Social Sciences (SPSS). Data was presented in the form of frequency distribution tables and charts that facilitated description and explanation of the study findings. The study found a positive correlation between ERP software adoption and firm financial performance, growth and learning, internal processes and customer satisfaction. The study recommended further study to be conducted on the impact of challenges of ERP software adoption on firm financial performance and risks associated with adoption of technology solutions especially in the era of cyber insecurity