Promoting the "artificial intelligence plus" initiative is considered a crucial leverage for cultivating new quality productive forces, and evaluating its microeconomic consequences is of substantial practical significance for optimizing capital market resource allocation. Corporate bonds and enterprise bonds issued by Shanghai and Shenzhen A-share listed companies from 2010 to 2024 were used as the research sample. The impact of artificial intelligence (AI) on corporate bond credit spreads and its underlying micro-mechanisms were empirically examined. The findings indicate that AI adoption significantly reduces corporate bond credit spreads. Mechanism analysis reveals that mitigating information asymmetry and suppressing debt default risks are vital micro-channels through which AI exerts its credit governance effects. Heterogeneity analysis demonstrates that the mitigating effect of AI on credit spreads is more pronounced among firms with poorer information environments and higher risk exposure, reflecting a distinct "timely assistance" marginal governance effect. Specifically, the reduction in corporate bond credit spreads driven by AI is more significant for enterprises with low levels of information disclosure and smaller firm sizes. Furthermore, this reduction is more prominent for enterprises located in regions with low marketization levels and those with poor internal control systems. The cross-disciplinary research between asset pricing and technological transformation is extended. Empirical evidence and policy implications are provided for the comprehensive implementation of the "artificial intelligence plus" initiative and the promotion of high-quality development in the real economy.