This paper focuses on understanding the transformative potential of active citizenship in green space governance. Through an in-depth case study, we show how citizens promoted the redevelopment of a brownfield into a green space, but eventually also contributed towards a broader co-creative shift in local governance. In this process, we highlight how a shift in citizens’ activities from contestation towards collaboration led to the uptake of citizen-driven discourses and activities in spatial planning. The social connectivity between governance practices is of key importance in this transformation—successful governance practices that involve active citizens can inspire others. Even so, transformation is often a slow and path-dependent process which also depends on an enabling policy environment. Cooperating with authorities provides citizens with power, but also requires alignment with official rules. Creating and maintaining effective partnerships will remain a challenge for citizens and policymakers that strive for societal transformations.