This study examines the impact of social insurance contributions on corporate environmental investments. Adopting a quasi-natural experimental design based on the implementation of 2011 Social Insurance Law in China, we employ a difference-in-differences model and find that the increase in social insurance contributions prompts firms to increase their environmental investment. This effect is more pronounced for firms that exhibit higher labor intensity, and are located in regions with stricter environmental regulations, as well as those with politically connected CEOs. Our research provides valuable insights into the factors that influence firms’ environmental investment from the perspective of firm-government interaction.