Employee green behavior is widely recognized as a cornerstone of corporate greening, with evidence showing that organizations' environmental performance largely depends on workers' active engagement in sustainable practices. In this literature, transformational leadership—both domain-specific and general—has become the leading paradigm for explaining how leadership contributes to individual-level environmental performance. Over the past decades, several studies have explored its links with employee green behavior, including mediating mechanisms and moderating factors. However, this research remains scattered across disciplines, and the validity and empirical relevance of transformational leadership—general or environmentally specific—has not been systematically assessed. This paper addresses this gap through a systematic review of the empirical literature, conducted following PRISMA 2020 guidelines. Peer-reviewed articles published in English since 2000 were retrieved from Scopus, Web of Science, and ABI/Inform Complete. Two coders independently conducted the screening with the support of Rayyan.ai, yielding 39 eligible articles. Data extraction was performed using qualitative content analysis guided by the TCCM (Theory-Context-Characteristics-Method) framework, with additional subcategories introduced to enhance analytic depth. Findings showed that most studies were conducted in Asian contexts (e.g., China, Pakistan, India), primarily within private manufacturing organizations. The predominant theoretical frameworks comprise social-cognitive theories (i.e., social learning theory, social information processing), relational exchange perspectives (i.e., social exchange theory), and identity-based approaches (i.e., social identity theory). The most examined mediators were harmonious environmental passion, green self-efficacy, and green empowerment, while environmental concern and perceptions of green human resource management (GHRM) practices were the most studied moderating factors. Most studies relied on cross-sectional designs and measured leadership via individual perceptions, overlooking between-organization variance. Moreover, theory-driven studies were often absent, and in some cases transformational leadership was conflated with the overarching theoretical framework. Finally, inconsistent terminology in environmentally oriented transformational leadership was frequently observed. Based on these findings, theoretical, methodological, and practical recommendations are proposed.