Energy security risks and private sector development are inherently intertwined and serve as pivotal determinants in shaping the evolutionary trajectory of the renewable energy (RE) industry, especially in emerging economies, where the transition to sustainable energy constitutes a critical strategic imperative amid global climate change mitigation efforts. Against the backdrop of shifting global energy dynamics and escalating demands for low-carbon development, renewable energy investment (REI) has emerged as a cornerstone of sustainable growth; however, the dynamic mechanisms underlying its determinants in emerging economies remain inadequately explored via rigorous econometric frameworks. This study aims to empirically examine the heterogeneous impacts of energy security risks and private sector development on REI in BRICS nations, emblematic of major emerging economies, by adopting the state-of-the-art generalized method of moments (GMM) panel vector autoregressive (PVAR) model, complemented by the method of moments quantile regression (MMQR) for robustness validation. The empirical findings corroborate that both energy security risks and private sector development exert a statistically significant positive impetus on REI in these economies. The impulse response functions (IRFs) demonstrate that REI exhibits a positive response to exogenous shocks in energy security risks, attaining a peak around the 3rd period before exhibiting a gradual attenuation over the subsequent horizon until the 10th period. Conversely, the IRFs pertaining to the nexus between private sector development and REI reveal a persistently positive and incrementally strengthening trajectory across the 10-period time frame, indicating that sustained advancements in private sector development foster a progressive augmentation of REI. Furthermore, the Granger causality test results validate that energy security risks and private sector development constitute significant causal antecedents of REI, underscoring their predictive power in shaping investment dynamics. Robustness checks via MMQR confirm these findings, revealing that energy security risks drive REI primarily at lower to medium quantiles, while private sector development exerts a consistent positive effect across most quantiles. These findings shed novel light on the critical role of mitigating energy security vulnerabilities and nurturing private sector dynamism as viable pathways to catalyze REI in emerging economies, thereby furnishing evidence-based policy implications for policymakers and strategic insights for investors striving to expedite the global green energy transition.