In recent decades, stakeholder engagement had been gaining momentum in planning practice. More recently, at the heart of the discussions about collaborative endeavours stands the concept of co-creation, an umbrella term for multiple forms of collaboration between stakeholders, which is seen as an approach for fostering new and innovative solutions for highly complex challenges. Despite this idyllic representation, co-creation does not always lead to positive outcomes. One reason is that co-creation poses major operationalization challenges, which make it a significant subject for research. In this article, we explore the conditions that allow co-creation practices aimed at fostering innovation and creativity in infrastructure projects to take place and flourish. Based on the review of literature on co-creation, on the analysis of project-related documents, and on in-depth, semi-structured interviews with the stakeholders, this article follows the co-creation process of the Overdiepse polder project, part of the innovative Dutch water management programme 'Room for the River'. The results show that co-creation is an iterative process that depends on conditions related to the context, the characteristics of the stakeholders and their relationships, but also on the design and dynamics of the process. The results of this study can be of help to researchers, academics, and professionals interested in studying or applying co-creative approaches.