The subtropical ROPME Sea Area (RSA), comprising the Gulf, the Gulf of Oman and the northern Arabian Sea, is a heavily exploited sea region that experiences extreme environmental conditions, and for which climate change is expected to further impact marine ecosystems and coastal communities, sectors and industries. Climate change risk assessments provide a valuable tool to inform decision-making and adaptation planning through identifying and prioritising climate risks and/or opportunities. Using the first UK Climate Change Risk Assessment as an example, a marine climate change risk assessment was undertaken for the marine and coastal environment of the RSA for the first time. Through an extensive literature review and a workshop involving regional experts, marine and coastal climate change risks were identified, scored and prioritised. A total of 45 risks were identified, which spanned two key themes: ‘Risks to Biodiversity’ and ‘Risks to Economy and Society’. Of these, 13 were categorised as ‘severe’, including degradation of coral reefs and their associated ecological assemblages, shifts in the distribution of wild-capture fisheries resources, changes to phytoplankton primary productivity, impacts on coastal communities, threats to infrastructure and industries, and impacts on operations and safety in maritime transport. The diversity of risks identified and their transboundary nature highlight that climate change adaptation responses will require coordinated action and cooperation at multiple scales across the RSA. This risk assessment provides a crucial baseline for a largely overlooked geographic area, that can be used to underpin future decision-making and adaptation planning on climate change, and serve as a ‘blueprint’ for similar assessments for other regional shared seas.