Public environmental protection hotlines, as an important supplement to the government-regulated environmental governance model, can force enterprises to improve the efficiency of green governance by giving full play to the supervisory function of the masses. This paper takes the “12369” Environmental Protection Hotline of various provinces as the research background and selects A-share listed enterprises in China from 2013 to 2020 as the sample. The results show that the compulsory supervision method of public environmental protection hotlines can significantly improve corporate green governance performance. Transmission path analysis indicates that, on the one hand, from the perspective of deterrence effect, public environmental protection hotlines can enhance the government’s law enforcement efforts against non-compliant enterprises, urge enterprises to change their behavioral decisions, and increase investment in green environmental protection. On the other hand, from the perspective of incentive effect, public environmental protection hotlines can encourage the government to actively participate in environmental governance, expand the scope of environmental protection subsidies, and at the same time urge enterprises to carry out green innovation, ultimately achieving green transformation. According to heterogeneity analysis, the enabling effect of public environmental protection hotlines on corporate green governance is more significant in heavily-polluting enterprises and those with higher green awareness. In addition, public environmental protection hotlines can make up for the governance failure caused by the low efficiency of government environmental regulations, and a good legal environment can effectively improve the efficiency of public environmental protection hotlines in playing a supervisory role. In conclusion, this paper provides a new perspective on how to improve the construction of a green governance mechanism for enterprises.