Located in the Cantabrian Sea (NE Atlantic), 30 nm off the Asturian coast, “El Cachucho” was the first off-shore Marine Protected Area (MPA) to be declared in Spain. The area includes Le Danois Bank and its intraslope basin. It joined the OSPAR Network of MPAs in 2009 and, thereafter, was included in the Natura 2000 Network in 2011. The main reason for its declaration as MPA was the presence of the 1170 Reefs habitat included in Annex I of the EU Habitats Directive. In 2018, the MPAs Master Management Plan was under revision and its design criteria were subjected to evaluation. We used Marxan decision support tool to evaluate the MPA's management design criteria. This tool selects the most important conservation features, while minimizing the socioeconomic cost. First, the 1170 Reefs habitat was defined as the main environmental value. Specifically, we took into account the six large sized target species that are more representative of this habitat in the area: the sponges Asconema setubalense, Geodia cf. barretti and Phakellia robusta, the anthipatarian Leiopathes glaberrima, and the gorgonians Placogorgia sp. and Callogorgia verticillata. A spatial distribution map was produced for each species using Generalized Additive Models (GAM). We also considered the presence of spawning stocks of fish species which are present in the area as an important conservation value. Their spatial distribution was modeled through Maxent software. Additionally, for the socioeconomic cost, fishing effort of the different fisheries operating in the area was estimated linking VMS/Logbook data before and after the MPA was declared. The first results obtained with the Marxan tool were presented in public consultation, in the context of the LIFE + INTEMARES Project, to help in decision making within the new Management Plan. Thus, to improve the management measures aimed at the conservation of the environmental values of the MPA, an enlargement of the protected area to the West was proposed, and a more reasonable use of the buffer area to fishermen than that defined in the former Management Plan was suggested. Involving all stakeholders in the development of the management plan for this MPA is a decisive step for the creation and consolidation of an important network of MPAs in Spain. •Explain the methodology used to identify the main environmental and socio-economic values of El Cachucho MPA.•Analyze the current Management Plan of the MPA by ensuring the representativeness of the vulnerable habitats.•Ensure an adequate protection of the environmental values with a minimum socio-economic impact on local communities.•Describe how spatial planning approach may help in shaping and updating the boundaries and zones of MPAs.•Emphasize the relevance of actively involve all the stakeholders in the MPAs follow-up processes.