The current understanding of the dynamics of digital platforms and strategy for their concomitant ecosystems has emerged from an analysis of firms in Western market economies. Our contribution arises from a detailed study of the business strategies of the current leaders in the Chinese mobile internet industry—Tencent, Alibaba, and Baidu. We find that they have developed business models significantly different from those of US firms. We argue that these Chinese firms are developing a “platform business group” strategy predicated upon horizontal expansion through organic growth, acquisition, and the purchase of significant equity positions in vertical industries, such as ride sharing, online-to-offline commerce, and travel. As a generalization, their western counterparts were much more oriented toward vertical expansion integrating either upwards or downwards in their respective software stacks. A central component of the business group is an online payment system that operates with its other platforms to cross-feed traffic and use internal cross-platform personal data to customize its offerings to users. We show that the different environmental conditions in China versus Western market economies allow firms there to pursue different business strategies. The key differences are the market protection, different antitrust considerations, and different consumer behavior in mobile usage. Our extension of platform studies to non-Western market economies, with their different regulatory and consumer environments, enriches and extends theoretical and practical understanding of the development and dynamics of digital platforms.