<p>Large gaps in the implementation of climate policies pose a challenge to the achievement of greenhouse gas emission reduction targets. The lack of incentives in the cadre performance evaluation system (CPES) for climate governance constitutes a major cause of the implementation gap. Against this backdrop, the Chinese government has initiated a cadre performance evaluation system transformation (CPEST) in some counties, aiming to reshape the GDP-centred evaluation system. The study links the CPEST to six climate policies and assesses the impact of mixing the two on carbon emissions, employing county-level data spanning 2008-2022 and applying the Difference-in-Differences (DID) model. The study reveals notable synergistic effects between climate policy and CPEST. This effect is particularly prominent in mandatory climate policies and weaker in market-based climate policies. Further tests indicate that goal alignment significantly boosts the synergistic effect between CPES and climate policy when CPES shifts to prioritise green development. Time order is also important; climate policies implemented prior to CPEST contribute to enhancing the mixing effects of the two, yet this contribution is insufficient to generate synergistic effects. The mixing effects of the two are also affected by officials’ characteristics. Specifically, stronger mixing effects are more closely linked to officials who are younger, female, hold a master’s degree, and work in their hometowns. Mechanism analyses show that industrial structure upgrading, green technology innovation, environmental fiscal expenditure, and environmental penalties are the main ways in which policy mixing promotes carbon reduction. However, only the latter three mechanisms can generate policy synergistic effects. The study’s findings offer a significant reference for improving the efficacy of climate policies and reducing carbon emissions.</p>