Small and medium enterprises (SMEs) are crucial for any economy to grow and succeed, as evidenced in the Pakistani context, where SMEs contribute 30% of the country’s GDP. The objective of this study is to link green servant leadership (GSL) to the pro-environmental behaviour (PEB) of employees, particularly in SMEs, which very few studies have investigated. Building on social learning theory (SLT), this study developed and tested the conceptual framework that examines the impact of GSL on PEB and the mediating role of environmental passion (EP) and climate for green creativity (CFGC) among employees of SMEs. Data were collected from 460 middle-line managers, and a structural equation modelling (SEM) technique was applied to test hypotheses. The main findings revealed that GSL is impacted by the PEB, while EP and CFGC mediated these relations. The study findings demonstrated that a GSL with strong practices and values towards the environment could have a significant impact on employees’ PEB. This study fills the research gaps in different ways: First, by identifying the role of GSL on the PEB of employees. Second, by examining the dual-mediation mechanism of EP and CFGC between GSL and PEB. Third, this study is focused on the economic context of a developing country. The study offers guidelines for establishing PEB in SMEs. Multiple training programmes and effective planning procedures can achieve this milestone. The administration of SMEs should also give special consideration to pro-environmental issues in its hiring and recruitment practices for managers and leaders.