Abstract: The public participation mechanism is an important link in promoting the modernization of the national governance system and governance capacity, and also a key means of advancing the effectiveness of ecological and environmental construction. Based on the panel data of 282 cities nationwide from 2003 to 2021, the mechanism and path of how the public participation mechanism drives coordinated governance of pollution reduction and carbon emission reduction were explored from the perspectives of environmental information disclosure and public environmental appeals. The research findings are as follows: (1) The public participation mechanism significantly reduces the levels of environmental pollution and carbon emissions, which is conducive to promoting the coordinated governance of pollution reduction and carbon emission reduction. Among them, the effect of environmental information disclosure on pollution reduction and carbon emission reduction is better than that of public environmental appeals; (2) Heterogeneity analysis shows that the effect of environmental information disclosure and public environmental appeals on pollution reduction and carbon emission reduction in central and western cities is better than that in eastern cities, and the effect of pollution reduction and carbon emission reduction in non-provincial capital cities is better than that in provincial capital cities. For cities with a stronger promotion incentive, the effect of environmental information disclosure on pollution reduction and carbon emission reduction is more significant; for cities with a higher level of marketization, the effect of public environmental appeals on pollution reduction and carbon emission reduction is more significant; (3) The results of mechanism tests indicate that environmental information disclosure achieves coordinated governance of pollution reduction and carbon emission reduction mainly through policy synergy formed with environmental decentralization and ecological compensation, while public environmental appeals realize such coordinated governance mainly through policy synergy formed with environmental legislation and emission rights trading.