This study is a novel exploration of the psychological drivers of employee ecological behaviour (EEB) and well-being within Malaysian higher education institutions (HEIs). By integrating the Theory of Planned Behaviour (TPB) and Self-Determination Theory (SDT), this study's framework presents a unique theoretical model that links environmental knowledge, attitude, awareness, and consciousness to EEB and multidimensional well-being outcomes. Using survey data from 460 academicians across five HEIs, the study finds that environmental attitude and awareness significantly influence EEB, while environmental consciousness does not. Furthermore, EEB is positively associated with employee well-being across life, psychological, and workplace domains. This research contributes to the literature by linking TPB and SDT, two traditionally separate frameworks, into a holistic model that connects behavioural antecedents with well-being outcomes. It fills a critical empirical gap by applying this integrated model in a non-Western, underexplored academic setting, offering fresh insights into sustainability practices in Malaysian HEIs. From a practical standpoint, the findings underscore the need for institutions to move beyond awareness campaigns and implement structural supports that foster sustained ecological behaviour and enhance employee well-being, aligning with broader goals of corporate social responsibility and environmental management.