The core objective of this research is to investigate the association between Safety Leadership (SL), Safety Climate (SCL), Occupational Health and Safety Management System (OHSMS), and Safety Performance (SP). The research is grounded in 307 usable survey responses gathered from a hydropower construction firm, employing a cross-sectional design. The researcher used SPSS 23 and Amos 21 for structural equation modelling. Study results indicated that SCL serves as a positive complementary partial mediator between SL and SP. Additionally, the study presents a novel investigation into the moderating effect of OHSMS, demonstrating its supportive role in aligning SL with SCL to enhance sustainable SP outcomes. This research provides additional empirical support for the direct links between SL and SP, and between SL and SCL. Moreover, the study emphasizes the moderating effect of OHSMS within the mediated relationship of SL between SCL and SP. Additionally, this empirical evidence can serve as a valuable guide for managers and safety practitioners in developing countries to enhance the sustainable SP of hydropower construction firms.