Abstract: This research sought to determine how capital structure affected the financial performance of Kenyan listed energy and petroleum industry firms. The study main objectives were to determine how debt financing affected the financial performance of listed energy and petroleum sector companies in Kenya and how equity financing affected financial performance of listed energy and petroleum sector firms in Kenya. The theories that served as a guide for the study were: Pecking order theory and trade-off theory. This study adopted a correlational research design while dealing with the research objectives. A census method was adopted for purposes of analyzing the audited financial statements that were downloaded from the firm websites in arriving at detailed and well informed conclusions by employing Multiple regression, Correlation and Analysis of Variances techniques using the Statistical Package for Social Sciences (SPSS) software version 26 to establish the existence (or lack of it) of the study link between the dependent and independent variables. The study conclusions showed that the independent variables had a statistically significant effect on the financial performance of Kenyan listed energy and petroleum companies. The model correctly predicted the association between the variables based as depicted by the F-test. Recommendations on the variables were made for management consideration for future decision making where the study majorly recommended that the firms should use more internal equity to grow profitability as it does not involve costs of acquisition compared with external equity and debt finance and that in cases where external financing is required, management should base decisions on the finance option with the lowest investment risk and proportional costs.