In many sustainable urban innovation projects, the efforts, endurance and enthusiasm of individuals at key positions are considered a crucial factor for success. This article studies the role of individual agency in sociotechnical niches by using Kingdon’s agenda-setting model. Although strategic niche management is commonly used to study processes of urban innovation, the process of niche formation and the role of individual agency has been understudied. We will introduce the notion of the ‘niche entrepreneur’ as an actor who, analogous to Kingdon’s policy entrepreneur, connects the elements that are needed to develop a successful niche that allows learning for sustainability transitions. We will study the process of niche formation and the role of individual entrepreneurship therein, and identify the strategies that have been used by individuals to create a successful niche. This will be done for three cases in urban systems integration: the development of Eva Lanxmeer, a residential district in a drinking water retention area in Culemborg, the Netherlands; the transformation of the waste management practices of Lille Métropole Urban Community, France; and the development of the urban district Hammarby Sjöstad, Sweden. Our findings show that for the successful formation of niches, it is necessary to create ambitious, but clear goals and matching concrete operational plans; niche entrepreneurs may play the role of project champions that contribute significantly to the operationalization, monitoring and the effectuation of the original goals of the project; the strategies of niche entrepreneurs emphasize the building of coalitions and the securing of space for learning.@en