Institutional investors are essential stakeholders of the firm, and they care about firms’ sustainable development. In this study, we focused on a prevalent and essential type of information acquisition activity of institutional investors: corporate site visits, which refers to their trip to the firms’ headquarters and factories. We investigated the impact of institutional investors’ corporate site visits on firms’ likelihood of environmental violation. Using Chinese listed manufacturing firms in the Shenzhen Stock Exchange from 2009 to 2017, the econometric analysis shows that institutional investors’ corporate site visits significantly decrease firms’ likelihood of environmental violation. Moreover, this effect is more pronounced for firms in heavily polluting industries, firms not owned by the government, and firms with less institutional shareholding. Furthermore, we show that institutional investors’ corporate site visits prevent environmental violations by increasing firms’ environmental investment. Our study highlights the importance of institutional investors’ corporate site visits by showing that they are beneficial to the firms visited.