Abstract:Product modularity has become a common design strategy adopted by China’s manufacturing firms to achieve green development due to its innovation and green value. Meanwhile, the performance burden caused by green transformation is also the focus of firms. Motivated by this and based on the perspective of “green + innovation”, this paper proposes a theoretical framework that takes product modularity as the driving factor of firm performance and ambidextrous green innovations as the internal mechanisms (matching the differentiated innovation range selected by firms for different modules in the operational practice). Specially, combined with the customized trend, this paper proposes that the gap of "middle-level knowledge" (i.e., new knowledge of how products adapt to application scenarios) may cause risks in the process of collaborative R&D, so as to explore the moderating role of supplier involvement. Using data collected from 189 manufacturing firms in China, all hypotheses are tested. The empirical results show that: product modularity has a significant positive effect on ambidextrous green innovations and firm performance; ambidextrous green innovations have significant positive effects on firm performance; exploitative green innovation and exploratory green innovation play mediating roles and a chain mediating role between product modularity and firm performance; supplier involvement weakens the relationships between product modularity and ambidextrous green innovations. The results enrich the research on modularity theory and provide the theoretical guidance and management suggestions for firms to apply modular strategy to achieve green development meanwhile.