South America is experiencing profound land use and land cover changes. Their consequences on the Ecosystem Services (ES) supply and human well-being need to be diagnosed and monitored in order to support informed decisions both in management and territorial planning. The ES concept provides a key framework to evaluate human impacts on nature. The use of spatially explicit indicators able to characterize ES supply can turn operative the ES framework, enabling for sustainability assessment. The Ecosystem Services Supply Index (ESSI) is a synoptic indicator that estimates and maps supporting and regulating ES related to water and carbon dynamics from data provided by remote sensors of free access and wide spatial coverage. The ESSI merges two attributes of the Normalized Difference Vegetation Index (NDVI) annual dynamics: the annual average (NDVIMEAN, a proxy of total C gains) and the intra-annual coefficient of variation (NDVICV, an indicator of seasonality). In this article we proposed two objectives: 1) to describe the conceptual foundation of the ESSI and to gather the empirical support that shows its ability to explain the spatial-temporal variation in different ES, and to present a new case of empirical ESSI assessment, and 2) to synthesize the contribution of the ESSI in socio ecosystem diagnosis, monitoring and territorial planning stages in 8 existing cases of application. We also explored the links to the decision-making process by diverse stakeholders including local research and development institutions, NGOs and government agents. Cases corresponded to a wide range of situations from humid and dry forests to grasslands, and from local to subcontinental scales in southern South America. We found that ESSI was successfully applied for diagnosis, planning and monitoring processes which helped to better define interventions in management decisions and also to empower the most vulnerable stakeholders under territorial and environmental conflicts.