In recent years, green infrastructure has become a key tool for planning metropolitan natural areas and environmental features from a strategic and multifunctional perspective. Given the great diversity of theoretical and applied approaches currently being adopted for the analysis and design of green infrastructures, this paper addresses a critical review of this concept and explores its potential implementation through metropolitan-scale spatial plans. To this end, the article presents a comparative analysis of the three main Spanish metropolitan plans-Barcelona, Bilbao and Seville