Sustainability has become a critical focus in global supply chain strategies, yet small and medium enterprises (SMEs), especially in South Africa, face significant barriers in adopting green supply chain management (GSCM) practices. This study aims to investigate the drivers, barriers, and sustainability impacts of GSCM adoption among South African SMEs, with a focus on entrepreneurial contexts. Using a systematic literature review (SLR) guided by PRISMA, 45 peer-reviewed studies published between 2010 and 2025 were analysed. The study is theoretically grounded in the triple bottom line (TBL) framework and the diffusion of innovation (DOI) theory. Results indicate that GSCM adoption can significantly improve environmental, economic, and social sustainability. However, its implementation among South African SMEs is constrained by financial limitations, lack of awareness, technological gaps, and weak supply chain collaboration. Based on these findings, a theoretical framework was developed to explain the relationship between GSCM drivers, adoption barriers, and sustainability outcomes. The proposed framework is conceptual and was not empirically tested in this study. Therefore, future research should apply quantitative or mixed method approaches to validate and refine the model. This research contributes to sustainable entrepreneurship literature by offering a structured foundation for understanding GSCM integration in resource-constrained SME environments.