Drawing on cognitive-affective system theory, this study proposes that employees’ perceived green human resource management (HRM) influences their’ workplace green behaviors through two psychological processes: the cognitive and the affective route. By analysing 358 questionnaires collected from Chinese firms in the oil and mining industry, we obtain evidence in support of our predictions, finding that employees’ perceived green HRM positively impacts their voluntary workplace green behaviors and green creativity. Additionally, green psychological climate and harmonious environmental passion are found to partially mediate the relationship between employees’ perceived green HRM and voluntary workplace green behavior while harmonious environmental passion is found to fully mediate the relationship between employees’ perceived green HRM and green creativity. These findings shed light on the importance of green HRM in shaping employees’ proactive workplace green behaviors and uncover how green HRM transforms employees’ cognitive, affective, and motivational (CAM) factors into green actions.