In a platform supply network, a platform owner uses a digital platform to link other firms such as suppliers, customers, logistics firms and other service firms for resource combination to manage supply chains in a comprehensive manner. Resources from different providers are combined on the platform to create value for suppliers. The literature on the Service-Dominant Logic (SDL) has implied that resource density (defined as the optimal combination of resources) is key to value co-creation. Resource density is enhanced when the number and variety of resources and/or their combinability at the opportune time and place are boosted. Yet the process by which the platform owner, complementors (independent companies providing complementary services) and suppliers interact to make this happen is still unclear. This research aims to explore how these three kinds of actors interact to build a resource density situation that guarantees satisfactory value creation in a platform supply network. Based on a qualitative study of a Business-to-Business (B2B) e-commerce digital platform, we identify three mechanisms through which these companies achieve resource density. The findings demonstrate how the mechanisms for achieving resource density manifest in the platform supply network context. We reveal that resource density can be achieved at three different levels, and that artificial intelligence and digital platforms play key roles in optimizing resource density.