This paper examines how geopolitical risk (GPR) influences corporate sustainability through firms’ adaptive capacity. Using a comprehensive panel of Chinese A-share listed firms from 2010 to 2024, firm-level GPR perception is measured based on word2vec-driven textual analysis of corporate annual reports, and its impact on environmental, social, and governance (ESG) engagement is analyzed. The empirical strategy combines a quasi-natural experiment exploiting the 2018 U.S.–China trade conflict with instrumental-variable approaches based on firms’ overseas income exposure, aggregate GPR indices, and the Lewbel (2012) method to address endogeneity. We find that heightened geopolitical uncertainty, operating through tighter financial constraints and elevated managerial risk perceptions, leads firms to reallocate resources away from long-term, capital-intensive ESG engagement. Corporate resilience significantly moderates this effect. Firms with stronger innovation capability, strategic partnerships, and structural flexibility are better able to absorb geopolitical shocks and maintain ESG investment stability under geopolitical stress. By linking geopolitical shocks to firm-level adaptation and resource allocation, this study identifies resilience as a key determinant of whether corporate sustainability is preserved or retrenched in turbulent environments.