Using medical insurance (MI) to shift employees' health risks outside is an important risk management tool for modern firms. Existing studies usually treat firms' contributions to employees' MI only as a labor cost. However, contributing to MI also has indirect benefits, such as improved labor productivity and R&D innovation, which consequently increase corporate value. This paper studies the impact of firms' MI contributions for employees on corporate value, using social insurance collection system reform in China as a natural experiment. Results show that, first, the reform increases firms' contributions to employees' MI funds. Second, the increase has a positive impact on firms' market‐to‐book ratio. These effects can be explained by enhanced labor productivity, firm efficiency, and innovation. Heterogeneity analysis suggests that the effects are more pronounced for firms in high R&D industries, areas with high pollution, or areas with better medical and labor supplies.