This research examined the association of AMO-based Green Human Resource Management practices with environmentally responsible behaviour and perceived organisational environmental performance in India’s pharmaceutical sector.  The study used the ability–motivation–opportunity framework to distinguish among ability-enhancing, motivation-enhancing, and opportunity-enhancing green HR practices. Data was collected from 565 employees from different pharmaceutical firms in Himachal Pradesh, India. Validated multi-item scales were taken from Tang et al. (2018), Saeed et al. (2019), and Montabon et al. (2007) were used. The data was analysed using CBSEM in AMOS 27. The findings show that all three AMO dimensions are positively associated with environmentally responsible behaviour. Environmentally responsible behaviour is also positively associated with perceived organisational environmental performance and mediates the relationship between AMO-based Green HRM practices and perceived environmental performance within the tested cross-sectional SEM model. AMO practices explain 37.9% of the variance in environmentally responsible behaviour, and the full model explains 38.0% of the variance in perceived organisational environmental performance. The study contributes context-specific evidence from Indian pharmaceutical manufacturing and highlights employee behaviour as a key pathway linking Green HRM practices with environmental performance.