Grounded in social network theory, this study examines how institutional investors’network centrality shapes firms’ ESG performance using data from China’s A-share listed companies between 2009 and 2022. The empirical results show that a higher level of network centrality among institutional investors significantly improves firms’ ESG performance. Mechanism analysis indicates that this positive effect operates through three main channels: alleviating information asymmetry, amplifying external public pressure, and enhancing managerial risk awareness. Further analysis reveals that even non-shareholding institutional investors can also indirectly foster firms’ ESG improvement through information networks. Furthermore, the positive influence of institutional investors’ network centrality exhibits spillover effects across connected firms within the same network, collectively promoting higher ESG standards.