<p>The Construction of National Key Ecological Function Zones (NKEFZs) is of great significance for safeguarding national ecological security. Drawing upon the panel statistics for 1,492 county-level units in China covering the period 2006–2022, this research adopts the multi-period Difference-in-Differences (DID) model and mechanism test model to comprehensively investigate the effects of the Construction of NKEFZs on county-level ecological resilience (ER) and its operational mechanism. It is revealed that the implementation of NKEFZs can substantially improve county-level ER, with ER in the treated counties increasing by an average of 0.139 units relative to the control group following policy implementation, a result that persists through various robustness assessments. Mechanism analysis shows that the Construction of NKEFZs improves county-level ER through three primary channels: restraining industrial development intensity, facilitating industrial structure upgrading, and advancing green patent innovation. Heterogeneity evidence indicates that the measure possesses a more pronounced positive impact in eastern counties than in their central and western counterparts, and its impact is significantly greater in counties with high topographic relief compared to those with low topographic relief. Therefore, the government should continue to deepen policy implementation, implement targeted measures to enhance mechanism effectiveness, focus on regional characteristics to adopt differentiated strategies, and fully release the enabling role of policies in ER.</p>