["Corporate Social Responsibility and Environmental Management, EarlyView. ", "\nABSTRACT\nThis study explores the role of green human resource management (GHRM) and employees' green behaviour (GB) in enhancing firms' green performance. Specifically, it investigates how GHRM practices contribute to improving the firm's overall environmental performance by fostering employees' GB. In addition, it explores the link between green performance and firm performance. Using a quantitative approach, data were collected through a structured survey administered to 211 Spanish industrial companies, a context characterised by higher levels of environmental regulation than those in which most prior research on GHRM has focused. The results reveal a positive relationship between GHRM practices and employees' GB and between such behaviour and green performance. Furthermore, employees' GB is found to partially mediate the relationship between GHRM and green outcomes. This research contributes to the growing field of sustainable management by highlighting the key role of GRHM in enhancing environmental performance. It emphasises that this effect stems from GHRM's positive impact on fostering GB among employees in the underexplored context of industrial companies in a Western country. Based on these findings, the paper provides clear, practical guidance for organisations seeking to make environmental sustainability a part of their everyday operations.\n"]