Abstract Environmental sustainability is nowadays driving firms to not only develop internal green activities, but also extend toward green supply chain management (GSCM). The extensive application of external GSCM by firms can be partially justified from perspective of transaction costs. GSCM practices are often considered to be prudent because studies suggested that such practices have a positive impact on firm performance according to the resource-based view. However, crucial questions still surround the practice-performance relationship. First, what is the overall relationship between GSCM practice and firm performance? Second, under what situations is the relationship stronger or weaker? To answer these questions, this paper focuses on quantitatively analyzing extant literature published in the field of GSCM. A random-effects meta-analysis is used to synthesize the empirical results of 54 selected literature with 245 effect sizes. Besides, subgroup analysis and meta-regression are applied to test potential moderators that may influence the strength of practice-performance relationship. We find that, internal and external GSCM practices are positively related, and they are both positively related to firm performance. Particularly, their relationship with environmental (r = 0.518) performance is the largest, followed by operational (r = 0.481) and economic (r = 0.464) performance. In addition, test of moderators discovers that industry type, ISO certification, export orientation and the cultural dimension of uncertainty avoidance all have moderating effect on the practice-performance relationship. Discussions and limitations are further addressed.