Managing default risk in state-owned enterprises (SOEs) is critical to national economic security and financial stability. The advancement of national audit informatization, centered on the Golden Audit Phase III Project, constitutes a key measure for risk prevention. Against the backdrop of Phase III’s implementation, this paper selects A-share listed SOEs from 2013 to 2024 and employs a DID model to examine the impact of this initiative on SOEs’ debt default risk. The findings show that the initiative significantly mitigates debt default risk in SOEs. Mechanism testing indicates risk mitigation through improved information quality, strengthened corporate governance, and enhanced supervisory coordination. Heterogeneity analysis shows that this effect is more pronounced in eastern and central regions, among SOEs without industry-finance integration, and among those with higher big-data application. Further analysis reveals that the national audit informatization initiative has been effective throughout the process of dynamic reforms, with Phase III demonstrating a stronger impact on SOEs’ debt default risk than Phase II. Additionally, Phase III exerts the most direct risk-mitigating effect on local SOEs while also significantly affecting centrally administered SOEs. Economic consequence testing reveals significant industry and regional spillover effects of national audit informatization in SOE risk governance. By reducing debt default risk, the initiative significantly improves SOEs’ development quality. This paper offers practical implications for deepening the national audit digital development strategy and for preventing systemic financial risks.