The ONEPlanET project aims to develop a common nexus modelling framework to simulate and evaluate pathways to define a more sustainable future in Africa through the deployment of renewable energy infrastructure. In this way, it will be possible to stimulate a green energy transition in the continent as well as a decarbonization of existing energy plants. The ONEPlanET model will be tailored to the needs of different stakeholders and end-users (public and private actors, policy and decision-makers, experts, and citizens) and will be totally open source to stimulate its future upgrades. The model will include information on Water, Energy, Food (WEF) and interlinkages with other sectors as Economy, Ecosystems, Society, Climate and Land for delivering a multi-sectoral assessment consistent with socio-economic and climate scenarios. The ONEPlanET modelling approach will integrate Earth Observation data (e.g., Copernicus, ESA or GEOSS), statistical data and information from basins to national and regional, via three representative case studies in the Songwe (Malawi/Tanzania), Inkomati-Usuthu (South Africa) and Niger (Nigeria) river basins, which show different types of basins and socio-ecological systems. ONEPlanET will help to better understand the interactions between Nexus sectors to deliver sound technical and policy recommendations towards the implementation of energy infrastructure to build a more climate neutral and resilient society.