External Pressure and Green Human Resource Management (GHRM) drive green initiatives but their synergistic effects on Green Supply Chain Initiatives (GSCIs) are yet to be explored. Moreover, results of three elements of the triple bottom line sustainability show mixed relationship in the order they affect each other. Drawing on the Natural Resource-Based View (NRBV) and institutional theory, this research empirically investigates a theoretical model by examining: first, the impact of GHRM practices and external pressures on GSCIs; second, the impact of GSCIs on environmental performance; and third, their sequential effects on social and economic performance. Cross-sectional survey data from 168 SMEs in the Food and Beverage sector in Australia were analysed using structural equation modeling. Results reveal that GHRM practices and external pressures have positive effects on GSCIs that in turn affects sequentially on environmental, social and economic performance. Social dimensions, however, have no significant effect on economic performance. Meanwhile, GSCIs mediate the relationships between GHRM practices and external pressures and environmental performance. Implications are drawn.