With consumers increasing in environmental awareness, manufacturers have integrated green R&D into their strategies, aiming to grasp the green market. However, manufacturers may be too bullish on the market potential of green products and maintain an optimistic attitude toward green R&D. Despite having an optimistic attitude, manufacturers often have no demand information advantage over downstream retailers due to their position in the supply chain, away from the market. It is worth exploring what impact optimistic green R&D in a sustainable supply chain with demand information asymmetry will have. Previous studies have not managed to reveal this. In this study, a stylized model is introduced to explore this question. The main findings are as follows: (1) optimistic green R&D increases the feasibility of the retailer sharing demand information, which facilitates information communication in the sustainable supply chain; (2) in most cases, optimistic green R&D does not bring higher profits for the manufacturer, yet is likely to allow the retailer to earn more, thereby resulting in a loss–win outcome; and (3) depending on the green R&D efficiency of the manufacturer and the consumer’s environmental awareness, optimistic green R&D may not generate higher environmental benefits.

Against the backdrop of the synergistic development of digitalization and green transformation, supply chain digitalization (SCD) plays a significant role in supporting companies’ green development; however, it remains unclear how it affects greenwashing. This study uses supply chain innovation and application pilots as a quasi-experimental design and employs panel data from Chinese A-share listed companies (2009–2024) and the difference-in-differences (DID) method to conduct theoretical analysis and empirical testing. The results indicate that SCD significantly curbs corporate greenwashing; this conclusion holds even after robustness tests such as parallel trends tests, propensity score matching, and placebo tests. Mechanism analysis indicates that SCD curbs corporate greenwashing through two channels: (1) enhancing corporate green technological innovation capability and (2) alleviating information asymmetry. Heterogeneity analysis indicates that SCD’s inhibitory effect on corporate greenwashing is more pronounced among firms with higher debt financing costs, greater institutional investor ownership, and greater media coverage. From the perspective of SCD, this study offers insights for promoting corporate green transitions and enhancing ESG transparency, while providing practical guidance for government regulators to combat greenwashing.