Environmental (E),social (S),and governance (G) has been under the limelight for the global corporations. Given this trend, growing number of firms pursue sustainability by enhancing the level of ESG. This paper especially focuses on firm’s internationalization as an important antecedent of corporate sustainability. With Korean MNEs’ listed on Refinitiv ESG Index, we propose that the degree of internationalization has positive influence on the level of corporate sustainability. We further test how internal (i.e., visibility, research and development intensity) and external characteristics (i.e., industry munificence, industry dynamism) of the firm moderate the relationship between internationalization and sustainability. Using a sample of 406 publicly traded Korean firms from 2016 to 2018, we found that firm’s degree of internationalization has positive impact on the level of corporate sustainability. Our results further show that such relationship is more pronounced when a firm has high level of visibility, research and development intensity, and industry dynamism. However, we do not find the moderation effect of industry munificence. We conclude that high degree of internationalization increase the level of sustainability to meet various stakeholder’s interests.