This study examines the influence of sustainability disclosure on a firm’s financial performance in the energy sector, taking into account the role of ownership concentration as a moderating factor. This study utilized secondary data from 239 energy companies from the Belt and Road Initiative (BRI) nations from 2009 to 2022. This study employed the Common Correlated Effect Mean Group and the Pooled Mean Group estimators for the analysis. To determine which component of sustainability disclosure influences a firm’s financial performance, this study divided the measurement of sustainability into three themes: environment, social, and governance. The findings revealed a positive relationship between environmental disclosure and financial performance. Similarly, we found a positive relationship between social disclosure and financial performance. However, governance disclosure does not contribute to financial performance. Furthermore, we found that ownership concentration positively moderates the association between environmental disclosure and financial performance, as well as social disclosure and financial performance. The results suggest that energy firms in developing countries should prioritize disclosing their environmental and social policies to ensure long-term financial performance.