The rise of digital platforms as a new form of business organisation concentrates power in the United States and China. Platform capitalism further intersects with and reinforces pre-existing trends towards state capitalism, where states more actively direct economies in response to economic turbulence and heightened geopolitical tension. The concentration of global business power within two states, combined with the increasing capacity for these states to leverage and direct platform activities for their own geopolitical–economic ends, has catalyzed the rise of ‘state platform capitalism’ (SPC). This paper develops the notion of SPC as an emergent logic of competition for both states and firms – in particular, the ways in which Beijing and Washington instrumentalise and mobilise domestic platform firms in pursuit of geopolitical–economic objectives, while platforms become increasingly interdependent with their home state institutions. Competition in the global political economy is increasingly centred on the recruitment of users and nations to these rival state-platform nexuses (national ‘stacks’) as a means of establishing and exercising extraterritorial economic and political power. Empirically, we identify variations between American and Chinese modes of practicing state platform capitalism, and we examine three axes within which this competition unfolds internationally: currencies, standards and cybersecurity.