The existing literature on government debt has predominantly focused on its influence on economic growth, with relatively limited attention paid to its ecological implications. Government debt, as an important financial tool, plays an essential role in improving the quality of economic development, yet its impact on sustainable governance remains underexplored. Against this backdrop, this paper investigates the relationship between government debt and carbon reduction using a sample of Chinese listed companies from 2010 to 2023. After excluding missing and financial firm data, our final sample includes 26,535 observations. We obtained these data from the China Security Market Accounting Research (CSMAR) database and the Wind database. This study utilizes ordinary least squares (OLS) as the baseline regression and identifies a significant positive impact of government debt on carbon emissions. Further, the moderating analysis suggests that the positive impact of government debt on carbon reduction is particularly stronger in state-owned (SOEs) and heavily polluting enterprises. To ensure the robustness of these findings, we also use fixed-effects models and the generalized method of moments (GMM), validating the consistency of the findings. This research provides critical practical and theoretical insights for regulators and adds to the prevailing body of literature on emissions reduction.