Sustainable urban policies constitute an important lever for cities seeking to transform into more equitable and adaptive systems. The ‘15-minute city’ model, which promotes proximity and access to essential services, offers a promising framework but requires effective collaborative governance. This article examines how the local government of Milan implements such policies. Drawing on a qualitative case study, we analyse how the municipality combines multi-stakeholder governance with a strong focus on social impact by funding for-profit and non-profit organizations to deliver services in vulnerable neighbourhoods. The findings reveal both opportunities and tensions: although managerial tools such as the theory of change facilitate coordination and outcome measurement, tensions persist around inclusivity, the sidelining of social actors, and the difficulty of moving from consultative participation to advanced collaborative shared governance.