This paper empirically analyzes the relationship between corporate governance and capital market risk using A-share listed companies in China’s Shanghai and Shenzhen markets from 2008 to 2022 as a research sample. The study finds that corporate governance decreases capital market risk using new risk measurement at the firm level. Further analysis shows that such an effect is more pronounced in the sample of private companies, companies with a higher degree of indebtedness, and companies with a lower concentration of power. This paper’s findings help us better understand corporate governance’s role in stock risk and provide theoretical support and empirical evidence to improve the stability of the financial market in emerging markets.