Firms face significant risk when they adopt digital supply chain systems to transact and coordinate with their partners. Drawn upon modular systems theory, this study proposes that system modularity mitigates the risk of adopting digital supply chain systems and therefore motivates firms to digitize more of their supply chain operations. The study theorizes how the risk-mitigating effect of system modularity can be enhanced by the allocation of decision rights to the IT (information technology) unit. The main logic is that IT managers with more domain IT knowledge can better utilize their knowledge in decision making to achieve effective system modularity. We tested these theoretical propositions using a survey study of Chinese companies and found empirical support. We also found that the allocation of decision rights to the IT unit does not directly mitigate the perceived risk of digital supply chain systems, which highlights the role of decision allocation to the IT unit as a key moderator in risk mitigation. The study generates theoretical and practical implications on how IT governance and system modularity may jointly mitigate risk and foster supply chain digitization.