<p>Greenwashing is a growing concern that demands immediate attention. Based on legitimacy theory and the attention-based view, this paper investigates whether retail investors’ environmental concerns expressed through digital platforms promote or inhibit corporate greenwashing. This paper utilizes the ERNIE large language model to construct an “environmental concern” index and examines the relationship between retail investors’ environmental concerns and corporate greenwashing, employing a sample of Chinese firms. The findings indicate that retail investors’ environmental concerns can effectively inhibit corporate greenwashing by increasing environmental comment letters and strengthening executive environmental awareness. We also find that regulatory enforcement, female executives, and executives’ climate change experience strengthen this effect, but state ownership weakens it. Furthermore, when retail investors raise more detailed questions and firms provide more specific, prompt, and detailed responses, this effect becomes stronger. This paper offers a novel perspective on the effect of retail investors’ environmental activism on greenwashing governance in the digital era.</p>