Radically innovative products and services are frequently developed and commercialized by new ventures. In this context, entrepreneurs may face the challenge of coordinating a complex network of actors in the presence of individual and collective uncertainties. Previous literature on entrepreneurship has focused on how entrepreneurs manage individual uncertainties (those that affect a single firm) rather than collective uncertainties that also affect members of the innovation ecosystem, which in turn may fundamentally affect the survival and growth of new ventures. Drawing on five longitudinal, inductive, in-depth case studies of start-ups and their innovation ecosystems, we find that current approaches for coping with individual uncertainties do not consider the impacts of uncertainties and actions on the innovation ecosystem partners. In that sense, entrepreneurs themselves may contribute to the propagation of uncertainties in the innovation ecosystem. We also identify processes by which entrepreneurs manage collective uncertainties in the innovation ecosystem, i.e., perceiving collective uncertainties, bridging uncertainties, conducting collective learning experiments and building a common template. This study improves understanding of how entrepreneurs act in uncertain environments.