The phenomenon of transformation from an internal platform to an external platform has attracted increasing research attention. However, the transformation process is still unclear. This study aims to uncover how internal platforms transform into external platforms. By adopting a case study method and taking resource orchestration as a theoretical lens, our findings generate a three-stage process model, which specifies the relationships among strategic sense-making of platform owners, resource orchestration, and capability in the path breaking, path creation, and path dependence stages. This study contributes to understanding the transformation process from an internal platform to an external one and thus bridges the literature on internal platforms and external platforms.