This study investigates the influence of green labor mobility on human capital breadth among employees of selected Small and Medium Enterprises (SMEs) in Ekpoma and Uromi, Edo State, Nigeria. Anchored in human capital theory (Becker, 1964; Schultz, 1961), the study employs a descriptive survey research design using primary data from 237 employees across 45 SMEs. Green labor mobility is conceptualized as the systematic rotation and movement of employees across environmentally-oriented functions, while human capital breadth is operationalized along four dimensions: technical environmental skills, sustainability management knowledge, stakeholder engagement capabilities, and systems thinking competencies. Data were collected through a structured questionnaire and analyzed using descriptive statistics (frequencies, percentages, means, standard deviations) and inferential statistics (Pearson correlation, simple linear regression, ANOVA) via SPSS v26.0. Findings reveal that green labor mobility exists at a low extent (Mean = 2.47, SD = 1.09), with informal knowledge sharing (Mean = 3.12) prevailing over formal rotation systems (Mean = 1.89). Human capital breadth registers at a moderate level (Grand Mean = 2.70, SD = 1.15), with technical environmental skills most developed (Mean = 2.89) and systems thinking least developed (Mean = 2.51). Regression analysis confirms a statistically significant positive relationship (β = 0.612, p < 0.001, R² = 0.375), indicating that green labor mobility explains 37.5% of the variance in human capital breadth. The study concludes that green labor mobility, despite being underutilized, represents a potent mechanism for building sustainability capabilities in Nigerian SMEs. Recommendations include formalizing green job rotation programs, establishing green competency standards, and providing technical assistance for green HR development. 

Keywords: Green Labor Mobility; Human Capital Breadth; Green Human Resource Management; Small and Medium Enterprises.