The objective of this study is to examine the impact of green supply chain management (GSCM) on operational performance as moderate of firm size and percentage of exported products. Based on the feedback of 313 manufacturing enterprises in four sectors (electronics, agriculture, food, textiles) operating in Vietnam, this study found some important findings. Firstly, GSCM has a positive and significant influence on the operational performance of businesses in Vietnam. Secondly, the resulting effect of implementing GSCM is better for enterprises with large scale and high export rates. This has reaffirmed the need to improve the overall supply chain management and green supply chain of this group of businesses. Overall, the findings suggest that improving GSCM practices is important not only for businesses in developed countries but also for businesses in emerging economic regions such as Vietnam.