The components of free cash flow and a firm’s capital structure affect the value of the firm. A firm with efficient cash management and optimum capital structure tends to have a better firm value. The current study examines the effect of capital structure and free cash flow on energy firms’ efficiency in Saudi Arabia. The data required for analysis were collected from a sample of seven energy companies from 2014 through 2022. The study used Data Envelopment Analysis to measure the efficiency of energy firms. Further, the simple regression and Generalized Linear Model were used to estimate the results. The study reports an average efficiency score of 1.13 for the energy companies, showing an efficiency increase. The results of simple regression are consistent with the results of the Generalized Linear Model. The study findings demonstrate that the association of firms’ capital structure is positive and significant (with a coefficient of 41.60, significant at a p-value of 0.01) to the efficiency of Saudi Arabian energy firms. Further, current research results indicate that firms’ free cash flows negatively affect the efficiency (with a coefficient of –0.79 and insignificant) of Saudi Arabian energy firms with no evidence. Therefore, the study accepts the association of free cash flow and firms’ efficiency as positive and rejects the alternative hypothesis that there is a negative association between free cash flow and efficiency in Saudi Arabian energy firms. AcknowledgmentThe researcher extends appreciation to Prince Sattam Bin Abdulaziz University for funding this research through the project number 2023/02/25856.