A growing demand at several levels of territorial government concerns the need for tools to support policy-making oriented towards sustainable planning. That of Ecosystem Services (ES) represents a well-structured and robust methodological framework for developing tools to assess environmental performances and territorial transformations linked to different development needs. The paper fits into this frame by proposing an analytical framework based on the ES multifunctionality approach, i.e., the joint provision of multiple ES, and applying it to the Italian national context. The methodology defines a spatial model based on three aggregate indices (abundance, diversity, and richness) assessed considering the Provinces as reference territorial units. Derived from ecological disciplines, these three dimensions of ES multifunctionality describe the variability with which territorial units deliver multiple services for community well-being and support the analysis of the relationships between anthropic components of territorial systems and the ecosystems’ multifunctionality. The evaluation of how the three indices’ spatial distribution varied as a result of land-use changes in the period 2000–2018 allows us to highlight specific aspects of territorial units useful to improve the knowledge framework from a sustainable planning perspective. The results highlight its potential to support decision-making processes and formulate recommendations for sustainable spatial planning.