Based on social network theory, this study investigates the impact of supply chain network structure on firms’ substantive innovation and examines the moderating role of CEOs’ general ability. Using a sample of Chinese listed firms from 2005 to 2020, the research finds that both network breadth and depth exhibit an inverted U-shaped relationship with substantive innovation, while spatial complexity has a positive effect. CEOs’ general ability weakens the marginal effects of breadth and depth and strengthens the positive effect of spatial complexity. When economic policy uncertainty increases, the effects of network depth and spatial complexity on substantive innovation become more salient, whereas the inverted U-shaped relationship between network breadth and innovation becomes attenuated. These findings suggest that the structural dimensions of supply chain networks respond differently to innovation in dynamic environments.