Purpose – This study aims to examine the effects of Top Management Commitment to Greening the Workplace (TMCGW) on Employee Green Behavior (EGB) through the mediating role of Green Human Resource Management (GHRM) and employee Green Self-Efficacy (GSE) at universities in Bangladesh. In addition, it aims to find the differentiating impact of these relationships between academic and non-academic employees in the university. Design/methodology/approach – Researchers employed partial least squares structural equation modeling (PLS-SEM) in an empirical study grounded in a conceptual model derived from existing literature. The sample size is 288 Bangladeshi university employees: academics (171) and non-academics (117). The study is non-random, particularly convenient sampling with self-administered questionnaires for data collection. Findings – The overall sample’s findings have revealed that TMCGW positively affects GHRM, which in turn fully mediates the relationship with EGB. In the overall sample, TMCGW also positively affects employee GSE, which in turn fully mediates the relationship with EGB. In addition, in the academic sample, TMCGW has a positive influence on employee GSE, which in turn fully mediates the relationship with EGB; however, GHRM doesn’t mediate the relationship between TMCGW and EGB. Furthermore, in the non-academic sample, TMCGW positively affects GHRM, which in turn fully mediates the relationship with EGB, but TMCGW positively affects employee GSE, with GSE not mediating between TMCGW and EGB. The multi-group analysis also reveals that the differences are significant only in the relationship between GHRM and EGB. Originality/value – This study makes unique contributions in that TMCGW acts as an antecedent of GHRM, and employee GSE in the university, subsequently affecting EGB by applying signaling theory. The study also found a unique contribution of how this relationship varies between academics and non-academic employees in the university. This study helps university top management and HR professionals to develop appropriate policies to promote sustainable behavior among academics and non-academics.