Against the backdrop of rising uncertainties in the international situation and increasingly severe environmental protection pressure, the formation of global green trade barriers is accelerating, and carbon information disclosure is regarded as crucial for enterprises to compete in the international trade market. As an important practical carrier of China's institutional opening-up, the construction of pilot free trade zones is found to profoundly reshape the carbon information disclosure behaviors of enterprises in pilot areas through policy impetus and market pull, and to help Chinese enterprises smoothly integrate into the international market. From the perspective of institutional opening-up, the linkage effect between pilot free trade zone construction and green governance was explored. Taking Shanghai and Shenzhen A-share listed companies from 2010 to 2023 as samples, a difference-in-differences model was constructed to evaluate the impact of pilot free trade zone construction on the quality of corporate carbon information disclosure. The research finds that the establishment of free trade zones significantly improves the carbon information disclosure quality of local enterprises. Mechanism analysis indicates that free trade zone construction drives enterprises to release high-quality carbon information through three paths: expanding export scale, stimulating the growth of green investment and deepening managers' environmental cognition. Heterogeneity analysis shows that the policy effect is particularly prominent in cities with high export dependence, export-oriented industries and enterprises with a large proportion of export trade. Further extended analysis verifies that free trade zone construction achieves an overall improvement in corporate carbon information disclosure quality covering both information content and disclosure detail. Micro-level empirical evidence is provided for understanding the transformation of corporate green governance driven by institutional opening-up, and references are offered for the optimized design of pilot free trade zones.