Marine Spatial Planning (MSP) intends to create an improved, rational use of the ocean to reduce conflict among competing uses to achieve social, economic and environmental objectives. Systematic Conservation Planning (SCP) can contribute to MSP because it is also spatially explicit, deliberately seeks to reduce conflict and generates an evidence-based prioritisation of ocean-space use. Importantly, SCP includes biodiversity representation and persistence, is underpinned by quantitative targets and uses complementarity to achieve targets efficiently. Therefore, designing Ecologically or Biologically Significant Areas (EBSAs) using SCP improves their identification and delineation compared to current expert-based approaches, with greater likelihood of uptake in MSP because their SCP-based design deliberately avoids competing activities where possible. These principles are demonstrated in a case study of the Benguela Current Large Marine Ecosystem.