Taking China Pilot Free Trade Zone (PFTZ) as a new perspective of institutional environment optimization, this paper investigates its impact on corporate ESG performance. We find that the PFTZ positively enhances corporate ESG performance, which remains robust after various checks. The mechanism analysis shows that improving corporate environmental protection capacity and management efficiency are the main channels while strengthening labor protection and easing financial constraints can enhance the positive effect. Moreover, the positive effect of the PFTZ on corporate ESG performance is more pronounced in coastal regions, the service sector, and state-owned enterprises (SOEs).