The ESG advantages accumulated by enterprises in the process of sustainable development can become a new driving force for enhancing export competitiveness. Based on the data of A-share listed companies from 2008 to 2023, this paper examines the impact of ESG advantages on the export competitiveness of enterprises and conducts a mechanism analysis. Research shows that ESG advantages can enhance the export competitiveness of enterprises. Mechanism analysis indicates that the enhancement of an enterprise's export competitiveness by ESG advantages mainly relies on the income effect rather than the cost advantage. Specifically, it is manifested in the improvement of an enterprise's export competitiveness through the effects of R&D innovation, human capital enhancement and supply chain diversification. Heterogeneity analysis reveals that ESG advantages have a stronger promoting effect on the export competitiveness of enterprises with high reliance on overseas business, non-specialized and innovative enterprises, industrial enterprises, and regions with a high level of digital inclusive finance development. Further analysis reveals that the promoting effect of ESG advantages on export competitiveness increases with the degree of digital transformation of enterprises. Improvements in environmental governance practices can significantly enhance the export competitiveness of enterprises, while improvements in social and corporate governance practices are not significant. These research conclusions are conducive to providing decision-making basis and policy reference for enterprises to enhance their export competitiveness and promote the construction of a high-quality foreign trade pattern.