This study investigates the relationship between sustainable supply chain practices (SSCPs) and firm financial performance (FFP) through a comprehensive meta-analytic approach. Despite the growing emphasis on sustainability in supply chain management, prior empirical findings on the SSCP–FFP nexus remain inconsistent and fragmented. To address this gap, the study systematically synthesises evidence from 35 empirical studies published between 2005 and 2025, employing rigorous statistical techniques, including random-effects modelling and the Hunter–Schmidt meta-analysis method. The analysis evaluates the overall effect size and examines key moderating variables such as industry type, geographical context, firm size, and sustainability dimensions. The findings reveal a strong and statistically significant positive relationship between SSCPs and FFP, indicating that firms integrating environmental, social, and ethical practices into their supply chains tend to achieve superior financial outcomes. Specifically, practices such as green procurement, supplier collaboration, eco-design, and efficient logistics contribute to improved profitability, cost efficiency, and market performance. The results further demonstrate that the strength of this relationship varies across contexts, with stronger effects observed in manufacturing industries, larger firms, and regions with robust regulatory frameworks. The study contributes to the literature by reconciling conflicting findings and providing a generalisable understanding of the sustainability–performance linkage. It also offers practical insights for managers and policymakers by highlighting high-impact sustainability initiatives that enhance financial performance. Overall, the findings reinforce the notion that sustainability and profitability are complementary objectives, positioning SSCPs as strategic drivers of long-term competitiveness and organisational resilience.