Despite the surge of interest in platform cooperatives, we have a limited understanding of the dynamics of platform worker‐member participation in these cooperatives. Drawing on interviews with 21 senior leaders and founders of platform worker cooperatives, we investigate the dynamics of platform worker‐member participation, finding that these cooperatives experience some successes and many challenges. We then build theory about how four distinct features of platform worker cooperatives—the facilitation of multihoming, the physically untethered nature of work, the relatively high importance of scale as a strategic imperative, and the relatively low importance of initial platform worker‐member investment—influence these participation dynamics. We find that the platform and worker cooperative organisational models are in tension with one another when brought together within a platform worker cooperative, leading to positive and negative effects on participation.