<p>Facing challenges of resource constraints and environmental pressures in agriculture, sustainable agricultural development (SAD) represents a critical ecological and climate imperative. However, systematic evidence had been lacking on whether SAD effectively reduces agricultural carbon emissions (ACE) and advances agricultural carbon peak and neutrality goals. This study leverages China’s “National Sustainable Agricultural Development Demonstration Zone” policy as a quasi-natural experiment. Employing a synthetic difference-in-differences approach, we rigorously evaluated the policy’s causal impact on ACE. Results demonstrate that the SAD policy significantly reduced ACE, with robustness tests confirming the reliability of the conclusions. Further mechanism analysis reveals that SAD functions through dual pathways: strengthening environmental governance and increasing green fiscal expenditure. These findings provide critical empirical evidence for clarifying China’s green agricultural development objectives.</p>