The paper evaluates how the integrated Green Human Resource Management (GHRM) practices, such as the green recruitment and selection of employees, green sustainability training, green performance management, employee engagement and green compensation and rewards, play a role in green leadership leading to sustainability capacity of organizations. The research was based on Ability Motivation Opportunity (AMO) and resource-based view (RBV) conceptualizations, and the analysis was done using partial least squares SEM on 205 HR and the line managers of the manufacturing and service-based organization, upon using the questionnaires issued to the mentioned managers in ADANCO 2.2.1. Findings reveal that green recruitment and selection (E = 0.303), employee involvement (E = 0.350) and green compensation (E = 0.250) do play a significant role in influencing the green leadership with a combinational effect of 60.3% (R2 = 0.603). Green leadership plays an important role in exerting a favourable impact on sustainability (BR2 = 0.543) and helps to mediate among all three GHRM practices (Sustainability-mediated effects). Green leadership mediates between the GHRM behaviours of sustainability (0.189), recruiting (0.218) and promoting (0.155) in direct effect (p < 0.005). Although organizational green culture positively affects sustainability (156), it does not have such an effect on the connection between leadership and sustainability. This brings out the point that green leadership holds the key to sustainability.