ABSTRACT Organizational buyer involvement in green innovation is crucial for firms' sustainable development. However, the outcomes of such involvement remain unclear because of the mixed findings in existing studies, which call for further investigations into the underlying mechanisms and boundary conditions that shape the relationship between organizational buyer involvement and green innovation performance. This study aims to fill this gap by examining if, how, and when firms can benefit from organizational buyer involvement in green innovation. The findings indicate an inverted U‐shaped relationship between them. Additionally, organizational buyer involvement also has an inverted U‐shaped relationship with the supplier's knowledge integration capacity, which positively impacts green product innovation performance. Moreover, specific investments positively moderate the nonlinear relationship between organizational buyer involvement and knowledge integration. As such, this study adds to our understanding of the effects of organizational buyer involvement on firms' green product innovation performance, shedding new insights into green innovation and B2B collaboration literature.