Urban spaces are increasingly undergoing complex transformations that require long-term strategic visions based on alternative development models capable of engaging communities and planners. The multiple environmental, climatic, and social challenges faced by contemporary cities call for a rethinking of urban design through integrated approaches that combine resilience, adaptation, and cooperation with nature. In this context, Nature-based Solutions (NbS) represent innovative tools for regenerating urban spaces, managing climate risks, and generating environmental, social, and economic co-benefits [1]. This paper presents a theoretical and applied analysis of NbS in urban contexts, based on the investigation of planning tools and adaptation strategies adopted in diverse typological and spatial settings: Copenhagen, an anticipatory urban model for stormwater management with over 300 projects totaling € 1.8 billion [2]; New Orleans, a post-Katrina plan worth $ 220 million involving 90% of residents, which triggered a systemic transformation toward environmental justice and social resilience [3]; and further experiences in Milan, Singapore, Bogotá, and Barcelona. The reflection focuses on the effectiveness, inclusiveness, and durability of NbS, analyzing their strengths and critical issues. Regulatory and operational barriers—particularly in the Italian context—that hinder the structural integration of NbS into urban planning will also be addressed. The objective is to contribute to the methodological debate on the evaluation, adoption, and replicability of NbS in diverse urban contexts, highlighting the need for multidimensional assessment criteria that integrate environmental benefits, social impacts, economic sustainability, and models of participatory governance.