Kenya's energy sector parastatals encounter notable challenges pertaining to organizational performance. According to KenGen's 2020 annual report, there was a 4% decline in revenue, dropping from Shs. 45.9 billion in 2019 to Shs. 44.1 billion in 2020, indicating a decrease in organizational performance. Similarly, Kenya Power experienced a 25% decrease in profits, falling from Shs. 3.5 billion in 2022 to Shs. 2.625 billion in 2023. It is against this problem that the researcher assessed the effect of process supply chain integration on the organizational performance of energy sector parastatals in Nairobi County, Kenya. The study was anchored on relational exchange theory. A descriptive research design was adopted.The target population was the energy sector parastatals in Nairobi County, including the Kenya Electricity Generating Company Limited, Geothermal Development Company, Kenya Electrical Transmission Company, Energy and Petroleum Regulatory Authority, Kenya Power and Rural Electrification and Renewable Energy Corporation. Descriptive and inferential statistical methods were employed in data analysis. Descriptive findings revealed that the process supply chain integration affected the organizational performance of energy sector parastatals. The correlation analysis results showed that the relationship between process supply chain integration and organizational performance of energy sector parastatals was positive and significant (r=0.476**; p=0.000) at 1% significance level. Therefore, streamlined workflows, agile operations, and optimized processes determined the organizational performance. As per regression analysis results, the coefficient of determination was 0.226 thus 22.6% of variation in organizational performance was explained by changes in process supply chain integration. The study concluded that streamlined workflows allow organizations to minimize redundancies, thereby enhancing operational efficiency. Moreover, the agile operations enhance the response to market fluctuations and customer needs which consequently bolster revenue prospects, which means that process integration affected organizational performance. It was recommended that the energy sector parastatals should synchronize workflows, operations, and task interactions for seamless operations and enhanced efficiency. This will lead to increased operational efficiency, reduced redundancies, and minimized delays which will promote organizational performance.