The increased need by different firms to achieve operational performance has increased over the years. This has compelled firms to apply various strategies like Information Communication Technology and e-resourcing especially so as to attain desired performance. At Retail Supermarkets in Nairobi City County, Kenya, e-procurement has been used as a mode of daily transaction. However, information regarding how e-procurement has contributed to operational performance is limited. It is upon this perspective that this study examined the impact of e-procurement practices on operational performance of Retail Supermarkets in Nairobi City County, Kenya. The study reviewed the effect of e-tendering, e-sourcing and e-payments on the operational performance of retail supermarkets within Nairobi City County. The study was grounded on the Technology Acceptance Model 2. A positivism philosophy which commanded the use of quantitative approaches of research was used to underpin the study under a case study of Retail Supermarkets in Nairobi City County, Kenya as a firm or an enterprise. Under these approaches, administered questionnaires and interview guide was used to collect primary data from the procurement managers from the 94 registered retail supermarkets within Nairobi County. The sample respondents for the study were the 94 personnel from the supermarkets. The collected quantitative data was analyzed using descriptive, Spearman rank correlation and regression analysis. The collected research data was presented using tables and charts in line with the requirements of the study. The study was able to a response rate of 88% with only 12% of the sample participants not able to respond to the research. The study applied correlation tests and results established a strong positive effect of e-tendering, e-sourcing and e-payment on the operational performance of the retail supermarkets. Further, regression analysis pointed to a positive and statistically significant impact of e-procurement practices on operational performance of retail supermarkets in Nairobi City County. The study noted that 66.5% of the changes in the operational performance of retail supermarkets were as a result of e-procurement practices. The research concluded that electronic procurement practices have a significant impact on retail supermarkets performance. The study found out that adoption of e-payment, e-tendering and e-sourcing practices were significant predictors of operational performance of the supermarkets. The study recommends that managers ensure that adopted technologies are compatible with existing systems and resources to ensure compatibility and usability. The study also recommends that the organization management should invest in appropriate technologies that are easy to use and can be integrated across different stores and used with different devices since procurement processes involve multiple stakeholders with vested interests. The study recommends that policy makers campaign to promote infrastructural development to increase widespread use of e-procurement systems.