Urban crowdsourcing is a new form of open innovation that aims to develop smart cities. Using a qualitative approach with experts involved in the Casablanca Smart City project, this research contributes by investigating complex multi-stakeholder ecosystems. More specifically, this study identifies and examines the role of external stakeholders at each stage of the innovation process, and the resulting dynamic knowledge flows that help improve the process of urban crowdsourcing in the development of smart city solutions. Depending on the complexity of the innovation project, findings identify three primary stakeholders (citizens, public authorities, and private and public firms) and three secondary stakeholders (NGOs, universities, consulting companies). Results show at which of the four steps of urban crowdsourcing they intervene. Furthermore, the findings reveal a dynamic learning environment composed of two knowledge flows (“learning with” and “learning from” stakeholders).