As the institutional environment becomes increasingly complex, firms are facing greater external institutional pressures in their environmental, social, and governance (ESG) practices. This study examines the relationship between various institutional pressures-coercive, normative, and imitative-and the ESG performance of Chinese A-share listed companies between 2011 and 2021. The findings show that coercive, normative, and imitative pressures significantly contribute to corporate ESG performance, with these results holding after a series of robustness tests. The mechanism analysis reveals that these pressures enhance ESG performance by increasing ESG attention, with organizational slack positively moderating this process. Heterogeneity analysis shows that multiple institutional pressures have a greater impact on the ESG performance of non-state-owned companies, non-heavy polluters, and low-profit firms. This study expands the analysis of the consequences of external institutional pressures on firms' behavior and decision-making, as well as the study of mechanisms for sustainable and high-quality development. It also has important theoretical and policy implications for the practice of ESG responsibilities by firms.