In recent years, with the increasing awareness of sustainable development, corporate ESG (Environmental, Social, and Governance) performance has garnered widespread attention from investors and has had a sustained impact on long-term business operations. The mechanisms by which ESG performance affects corporations primarily include the "governance effect" and the "window-dressing effect." Aimed at high-quality development goals, what kind of impact does ESG performance have on corporate competitiveness? This paper attempts to explore the economic relationship between corporate ESG performance and corporate competitiveness in China's capital market through theoretical analysis and empirical testing. The research results show that ESG performance significantly promotes corporate competitiveness, particularly through the "social" dimension (S) and "governance" dimension (G). ESG performance significantly enhances corporate competitiveness by increasing corporate philanthropic donations and improving total factor productivity, demonstrating the "governance effect" of ESG. However, in the "environmental" dimension (E), ESG performance instead leads to an increase in corporate carbon emissions, which may indicate that corporate efforts in environmental areas are more for superficial appearance, exhibiting the "window-dressing effect" of ESG. This study reveals the crucial role of ESG practices in enhancing corporate competitiveness, providing theoretical support and policy implications for promoting corporate competitiveness and achieving high-quality development goals.