The ocean’s biodiversity supports the livelihoods of over three billion people, providing vital services, including food and nutrient cycling. However marine policy and resource management do not yet consider the latest scientific advances, even when the state-of- the-art operational models of the European Copernicus Marine Service (CMEMS) are used. The project’s objective is to enable CMEMS to deliver novel products that inform marine biodiversity conservation and food resources management, by fusing new data into innovative ecosystem models that integrate biological and abiotic components, habitats, and stressors of marine ecosystems. NECCTON will inter-link new models in the CMEMS systems, thus building novel capacities to simulate higher-trophic-levels, benthic habitats, pollutants, and deliver projections of climate change impacts. We will develop and exploit new data-processing chains, supporting CMEMS’ use of novel ecosystem observations, including new hyperspectral data from satellites, as well as available acoustic, pollution and omics data. We will fuse these new data and models by using innovative machine-learning algorithms to improve models and data assimilation methods. These developments will be applied in thirteen case studies, co-designed with fisheries and conservation managers as part of our pathway-to-impact, resulting in the demonstration of Technological Readiness Level 6 of NECCTON products. The project objectives will be achieved by a team of twenty-three world-class organizations with track records for all the key project components. It includes the CMEMS Entrusted Entity and core developers, who will promote the final uptake of NECCTON by CMEMS. On project completion, NECCTON will provide CMEMS with the scientific and technical