Microsoft’s rollout of its cloud platform, Microsoft Azure, required a fundamental transformation of its partner ecosystem. Before the rollout, most partners were either resellers who focused on selling licenses for Microsoft’s on-premises products or development partners who co-created on-premises products and services to expand Microsoft products. After the rollout, Microsoft aimed to foster an ecosystem with partners who would develop applications on the cloud platform to address the needs of customers and that would potentially scale on the platform. In a case study based on the introduction of the Azure platform, we lay out the challenges that Microsoft and its resell and development partners faced during the ecosystem transformation. Drawing on the responses to these challenges by Microsoft and its partners, we derive four governance mechanisms for enterprise software vendors during ecosystem transformation (e.g., establishing innovation clusters for specific target markets) and three adaptation mechanisms for ecosystem partners (e.g., developing their own IP). These mechanisms can guide incumbent companies and their partners as major technological shifts affect their ecosystems.