This article elaborates a conceptual framework to examine social sustainability in marine spatial planning (MSP). Based on a critical literature review of key texts on social sustainability in MSP and the broader sustainable development literature we show the need to elaborate a cogent and comprehensive approach for the analysis and pursuit of social sustainability linked to the sea. We then theorize social sustainability by developing a conceptual framework through integrating three dimensions: Recognition, Representation and Distribution. While these three social sustainability/justice features clearly overlap and are interdependent in practice, the conceptual thinking underpinning each of them is distinctive and when taken together they contribute towards conceiving social sustainability as a pillar of sustainability. Our approach can support an analysis/evaluation of MSP in that, first, its broad scope and adaptability makes it suitable to examine the wide range of claims, demands, and concerns that are likely to be encountered across different practical MSP settings. Second, it acknowledges the opportunities and challenges of assessing, implementing, and achieving social justice within a broader sustainability framework.