The aim of the study was to determine the effect of internal control system on the financial performance of Kenya Power Company. The objectives were to determine the influence of cash control systems on the liquidity management, establish how inventory control system has influenced the profitability and to assess how management information system controls influences the financial reporting and accountability of the Kenya Power Company. To achieve these the study adopted a descriptive research design in which 362 employee of Kenya Power were sampled purposively. Data was collected using questionnaires which were self-administered to the respondents. The data was analyzed using descriptive statistics such as frequency distribution and measures of the central tendency. The study also used inferential statistics mainly regression analysis to test the relationship between the dependent and the independent variables. The data was presented in form of charts, figures and tables. The study established that the organization largely employed cash control which enhanced the efficiency and effectiveness as cash payments were eliminated. The study further established that through the inventory controls the organization ensured that only the required stocks were available. The organization was also able to monitor its assets. The study established that the organization had effective accounting and internal control management system. The study established that the organizations asset base has greatly increased over time. Finally, the study established that there was a positive relationship between the organizations financial performance and the ICS. The study concludes that cash, inventory and systems controls influenced the financial performance of the organization. The study recommended that in order to enhance financial performance, the management should encourage state corporations to employ more cash controls, inventory controls measures and adopt information systems controls to enhance organizations efficiency in the operations.