["Corporate Social Responsibility and Environmental Management, EarlyView. ", "\nABSTRACT\nThis study examines how engineering trained chief executive officers (CEOs) determine firms' sustainability performance and greenwashing behavior in Australian listed firms from 2016 to 2024. Drawing on Upper Echelons theory and Imprint theory, we argue that engineering cognition influences environmental strategy by providing conservative, evidence‐based sustainability disclosures. We find that engineering CEOs are associated with weaker sustainability performance and lower greenwashing, indicating more credible and performance‐based environmental disclosure. Sustainability assurance moderates this association by increasing external verification of sustainability disclosures, encouraging firms to follow compliance‐oriented reporting practices and limiting CEOs' ability to influence disclosure credibility. Subsample analysis shows engineering CEOs are associated with stronger sustainability performance and an even greater reduction in greenwashing in technically intensive industries. Robustness tests using propensity score matching (PSM), entropy balancing, lagged models, and two‐stage least squares (2SLS) confirm the consistency of our results. This study shows that engineering expertise influences sustainability performance, disclosure quality and greenwashing. The findings provide insights for boards, regulators, and stakeholders interested in credible sustainability strategies.\n"]