The collaborative management of energy conservation and emission reduction (CMECER) can not only cut down energy costs and enhance energy security, but also effectively reduce pollutant emissions and safeguard the environment. In light of this, this study utilizes 278 Chinese cities’ data during 2007–2021 to analyze the impact of “National Energy Saving and Emission Reduction Comprehensive Demonstration Fiscal Policy” (ESERF Policy) with green fiscal at its core on CMECER. This study indicates ESERF policy can remarkably promote CMECER. The policy effect is achieved through enhancing green technology innovation and advancing industrial structure upgrading. Additionally, this policy exhibits a particularly significant effect when implemented in high economic development, high urbanization, and low CMECER cities. Simultaneously, when the policy is implemented in conjunction with innovation policy and information infrastructure policy, it is more beneficial for promoting CMECER. Moreover, this study proposes policy recommendations of reference value from three key aspects: enhancing the policy supervision and evaluation system, optimizing the mechanism system, and building a collaborative implementation cooperation framework.