Platform governance can contribute to the overall success of an ecosystem; however, what factors influence governance decisions remains to be understood. We propose that platform owners define and implement platform governance following their unique structure of ownership as digital platforms may be owned by a single, or many independent intermediaries. To compare platform governance across the specific ownership structures of incumbents, strategic alliances, and start-ups, this paper employs an embedded multiple-case study with 34 interviews and rich secondary data. Our findings illustrate the governance characteristics of each ownership structure and the influence of internal factors and the surrounding ecosystem on their governance decisions. We discuss governance strategies for each ownership structure regarding cost synergies, co-creation synergies, and growth opportunities. This study highlights the interdependence between platform governance and ownership structure and provides practical guidance for different platform ownership structures to design suitable platform governance strategies.