Although the synergy between green supply chain integration (GSCI) and lean management (LM) has garnered significant attention, the mechanism underlying how the GSCI-LM's synergy affects manufacturers' performance remains unclear. From the functional dimension, this research categorizes GSCI into green strategic alignment (GSA), green information sharing (GIS), and green process coordination (GPC). According to the resource orchestration theory, this study explores how GSCI prompts manufacturers' performance via LM and examines the moderating effect of supply chain risk management (SCRM). Employing the data of large-scale multi-industries and multi-countries manufacturing surveys and using regression analysis, this paper reveals that GSCI has positive effects on manufacturers' environmental and operational performance, and LM mediates the relationships of GSA-GIS and GSA-GPC. Moreover, SCRM strengthens the impacts of LM on GIS and GPC. This research contributes to literatures by unfolding the 'black-box' of the GSCI-LM's synergistic effects on manufacturers' performance and considers SCRM's moderating role.