This study explores the supply chain spillover effect of the national new-generation artificial intelligence innovation and development pilot zone policy and clarifies the internal mechanism through which the policy affects suppliers’ digital technology innovation. Based on supply chain data of Shanghai and Shenzhen A-share listed companies from 2007 to 2023, this research conducts a quasi-natural experiment on this pilot policy and adopts a multi-period difference-in-differences model to empirically test the spillover effect and its underlying mechanism. The results show that customers located in artificial intelligence pilot zones significantly promote suppliers’ digital technological innovation through two channels: the indirect driving effect of customer demand upgrading, and the direct enabling effect of resource supply. The spillover effect is more pronounced when customers have strong bargaining power, suppliers have high absorptive capacity, the geographic distance between suppliers and customers is greater, and regional intellectual property protection is stronger. Meanwhile, the policy also improves suppliers’ digital innovation quality and innovation input-output efficiency.