This paper analyses changes in the governance of urban nature in French urban policies over the past two decades. It demonstrates that the importance of “sustainable development” procedural principles has significantly declined in public policy agendas, a decline that has occurred alongside the rise to prominence of sectoral approaches based on performance and control, whether they focus on climate or urban biodiversity policies. Faced with these transformations in public action—namely the emergence of a centralized and sectoral management of urban policies ill-suited to the complex socio-environmental territories—collective movements in civil society are developing initiatives based on cooperation across territories. Consequently, the urban governance of nature reflects the conflicts between centralized policies and the composite and fragmented reality of the governance of nature in the city. We use the notion of “tinkering”, which refer to the general fragmentation of initiatives, actors, alliances and conflicts in the context of space usage in the field of urban nature, to describe these dynamics. Based on two studies of the urban policies developed by central French government authorities since the 1990s, we identify three principal discrepancies, based on three main separations, that illustrate “tinkering” with the governance of urban nature. The first relates to the discrepancy between “living nature” (biodiversity policies) and “physical-chemical nature” (in climate change policies) (Climate and biodiversity policies: sector-based governance). The second reflects the discrepancy between a technically oriented understanding of the environment and the sensory understanding of inhabitants (Discrepancies between representations and practices). Finally, the third concerns the different levels of action (Discrepancies in scale: the relationship between top-down and bottom-up governance).