The rapid development of cloud computing technology is transforming software vendors into cloud service providers. Unlike traditional sales of software, cloud computing services rely on close collaboration among participants in the computing ecosystem. This collaboration generates new modes of value co-creation. Using the SAP’s cloud computing services as a case, the paper delves into the interactions among software/platform vendors, infrastructure providers, and service providers, elucidating three value co-creation mechanisms: The exchange mode based on complementary resource sharing, the addition mode based on complementary resource addition, and the coalescence mode based on complementary resource synergistic integration. This study enriches the operational theory of platform ecosystems in the B2B context and offers managerial insights for the sustainable development of cloud computing ecosystems.