Based on the theory of information asymmetry, this paper takes A-share listed companies on the Shanghai and Shenzhen stock exchanges from 2011 to 2023 as the research sample. It uses text data from the Shenzhen Stock Exchange’s “Hudongyi” and the Shanghai Stock Exchange’s “e-Interaction” platforms, and constructs an investor interactive supervision indicator through large language models to explore the impact and mechanism of investor interactive supervision on corporate real earnings management. The findings indicate that investor interactive supervision can significantly inhibit corporate real earnings management. Heterogeneity analysis shows that this inhibitory effect is more prominent in enterprises with low ESG ratings, low media attention, private ownership, and high management myopia. Mechanism tests indicate that investor interactive supervision inhibits real earnings management through two paths: improving corporate information transparency and enhancing corporate resources acquisition capacity. This paper not only optimizes the measurement method of investor interactive supervision, but also reveals the micro-mechanism through which small and medium-sized investors participate in corporate external governance via online interactive platforms. It provides empirical evidence for improving the collaborative governance system of the capital market and contributes to promoting the high-quality development of the capital market.