Can Unified Green Product Certification Improve Corporate Environmental Performance? Evidence from China’s Certification Reform

Green product certification can reduce environmental information asymmetry, but most existing evidence evaluates the adoption of individual voluntary standards. This study examines a different institutional intervention: China’s government-led integration of previously fragmented green product standards, certification procedures, product catalogs, labels, and supervision. Using hand-collected certification records and firm-level environmental data for Chinese listed companies in heavily polluting industries from 2015 to 2024, we estimate propensity-score-matched difference-in-differences models. The reform is associated with lower sulfur dioxide emission intensity and higher environmental investment. The estimates show a more consistent environmental response under full-scope certification than under partial-scope certification, although subgroup significance alone is not interpreted as a formal coefficient difference. Post-certification emission effects persist but gradually attenuate. Additional analyses provide evidence consistent with a response centered on end-of-pipe treatment and with a domestic market premium, while the export effect is statistically insignificant. These findings show that system-level certification integration can improve environmental performance in a state-led emerging market, while persistent production transformation depends on the design of post-certification incentives and monitoring.