We examine whether free-speech protections influence corporate environmental performance. Using the staggered enactment of U.S. anti-SLAPP statutes in a stacked difference-in-differences design from 1990 to 2019, we find that these laws significantly reduce firms’ toxic emissions without curbing economic activity. Anti-SLAPP enactments also promote environmental investment through green innovation, abatement spending, and waste reduction management, and strengthen governance via improved sustainability oversight, ESG-linked executive pay, employee training, and supply chain management. The effects are stronger when stakeholder monitoring is stronger and when managerial incentives embed sustainability goals. Overall, free-speech protections generate powerful environmental benefits.