This study explores the relationship between ethical climateethical climate, green work climategreen work climate, environmental passionenvironmental passion, and pro-environmental behaviorpro-environmental behavior (PEB) among public sector employees in Malaysia. The researchresearchresearch aims to understand how ethical and green work climategreen work climates influence PEB, with particular attention to the mediating influence of environmental passionenvironmental passion. Drawing on social cognitive theorysocial cognitive theory (SCT) and social exchange theorysocial exchange theory (SET), we utilized a cross-sectional multilevel design, surveying 407 public servants across 37 organizations. The findings reveal that, while ethical climateethical climate negatively impacts PEB and green work climategreen work climate shows no direct effect, introducing environmental passionenvironmental passion as a mediator transforms these relationships into positive outcomes. This highlights the critical role of environmental passionenvironmental passion in aligning employee motivation with organizational sustainability goals. This researchresearch advances the theoretical understanding of public sector organizational behavior by demonstrating the pivotal role of environmental passionenvironmental passion in overcoming the challenges posed by ethical and green work climategreen work climates. These resultsresults offer valuable guidance for public sector organizations seeking to improve sustainability by fostering a work environment that nurtures environmental passionenvironmental passion.