Abstract: Under the background of the “dual carbon” goal and the deepening of the green development strategy, ESG governance, as an institutional arrangement linking corporate micro-level behavior with macro-level sustainable development objectives, has increasingly become a key driving force for the green transformation of industrial and supply chains. Mining industry, characterized by both resource intensity and environmental sensitivity, calls for in-depth exploration of how ESG compliance practices affect green production efficiency and through which channels such effects are transmitted. Based on balanced panel data of 162 Chinese listed mining enterprises from 2018 to 2023, this paper employs Huazheng ESG composite scores and its environmental, social, and governance sub-dimension scores as core explanatory variables, and adopts unabsorbed slack resources and absorbed slack resources as mediating variables. Using two-way fixed effects models and mediation models, this study systematically investigates the impact of ESG governance on green total factor productivity （GTFP） and the transmission mechanism of slack resources. The findings are as follows: firstly, ESG composite scores and all three sub-dimensions exert significant negative effects on GTFP of mining enterprises, with the governance dimension showing the largest negative effect, followed by the social dimension. This indicates that ESG compliance practices impose an efficiency constraint at the current stage, supporting the compliance cost hypothesis. The conclusion remains robust after lagged variable regression and instrumental variable estimation. Secondly, the mechanism analysis reveals a dual transmission pathway: ESG governance indirectly promotes GTFP improvement by reducing absorbed slack resources; since the direct effect is negative while the indirect effect is positive, the two operate in opposite directions, constituting a significant suppression effect. However, the mediation path through unabsorbed slack resources is not statistically significant. Thirdly, heterogeneity analysis shows that the efficiency constraint effect of ESG governance is more pronounced in state-owned enterprises, reflecting the greater compliance burden borne by state-owned mining firms. This study uncovers the dual pathway of “compliance cost versus management efficiency” from the perspective of slack resource allocation, providing empirical evidence for mining enterprises to achieve a dynamic balance between ESG compliance and green efficiency in the construction of sustainable supply chains.