The reform of Italy’s planning system is driving a shift towards a more integrated approach to spatial planning at multiple scales, emphasizing sustainable urban regeneration and environmental resilience. To achieve these objectives, public and private actors must adhere to innovative planning strategies that balance development with ecological preservation. Performance-based planning plays a crucial role in this transformation, employing regulatory and financial tools to incentivize the adoption of Nature-Based Solutions, Green–Blue Infrastructure, and Ecosystem Services within urban policies. The research for the Metropolitan City of Milan proposes a structured framework of environmental indicators to evaluate the effectiveness of planning actions at both metropolitan and municipal levels. By assessing the outcomes of urban interventions, these indicators facilitate more strategic financial planning, allowing the Metropolitan City to allocate resources based on sustainability performance. The model aims to enhance coordination across governance levels, ensuring that urban development strategies contribute to long-term ecological and social sustainability.