To create the science we need for the ocean we want in this United Nations Decade of Ocean Science for Sustainable Development and to support the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) value assessment, we systematically reviewed literature from the past 20 years (N = 375) that used conceptualizations of relational values in coastal and marine ecosystems of the Global South. We found four clusters of research highlighting specific characteristics. Cluster one (participatory and qualitative approaches) was defined by a focus on the relational value of cultural heritage and the production of qualitative social science data, often with a participatory approach. Cluster two (Indigenous and local ecological knowledges held by fishers and gatherers) linked to the explicit inclusion of Indigenous and local knowledges in research and to aspects of biodiversity and marine resources. Cluster three (ecological and environmental change) was determined by relational values of social relations and identity of residents and community members through the use of anthropological and ethnographic methods and linked to ecological and environmental change. Cluster four (recreation and quantitative data) was characterized by a variety of relational values, such as recreation and enjoyment, aesthetics and inspiration, or stewardship, and based on quantitative empirical social research methods mainly elicited from coastal users (such as tourists). We highlight (1) the most prevalent relational values; (2) the necessity to bridge dispersed research approaches; and (3) the possible negative impact of globalization, market pressure, and ecological degradation on relational values. Our lessons learnt are the challenge of conflating relational values with structures, institutions, or emotions; the necessity of accounting for dynamic influences on relational values; and finding ways to comparably quantify relational value categories. Our recommendations for future research are: (1) specificity regarding relational values and their object of value; (2) using transdisciplinary and participatory approaches; and (3) strengthening pro-environmental relational values for sustainability transformation.