The article focuses on an emerging regulatory tactic applied by governments around the world to promote environmental protection, termed here ‘regulatory eco-shaming.’ Regulatory eco-shaming refers to intentional publications made by administrative agencies regarding companies’ environmental misbehavior, designed to convey a negative message to the public to induce companies to comply with regulatory norms. For example, The Irish Environmental Protection Agency lists the top non-compliant Irish companies on its website. Social science scholars have explored the theoretical idea and practical framework of shaming companies by government regulators for poor environmental practices. Yet research into the legal implications of regulatory eco-shaming remain under-developed. This article suggests a legal theory for regulatory eco-shaming that balances effectiveness and fairness to ensure reasonableness and proportionality, aiming to guide administrative regulators, legislators and judges.