Coastal nature-based solutions (NbS) are increasingly recognized for their multiple benefits to socio-ecological systems, including climate mitigation and adaptation (e.g. conservation, restoration and sustainable management of coastal ecosystems for climate). National climate plans, such as the Nationally Determined Contributions (NDCs) developed under the Paris Agreement, include coastal NbS as a practical and effective action to help countries achieve their climate and biodiversity targets. However, the absence of a standardized NDC structure and the lack of guidance about how NbS should be included in NDCs can hinder access to external funding for developing countries and prevent transparent reporting on progress at the international level. In this context, our aim is to understand how coastal NbS are currently included in NDCs by evaluating their alignment with the IUCN Global Standard for NbS. Our analysis focuses on the description of coastal NbS in the NDCs of Pacific Small Island Developing States (PSIDS), as they are among the most vulnerable countries to the impacts of climate change. Overall, we find that, for the 22 coastal NbS examined in the NDCs of PSIDS, the degree of alignment with the eight criteria of the IUCN Global Standard is insufficient or partial, with slightly better alignment with the standard in revised NDCs than in original NDCs. We discuss opportunities provided by the standardization of the description of coastal NbS in NDCs, in terms of access to funding and stock taking to monitor the effectiveness of implementation and progress towards long-term goals. We also discuss the relevance of using the IUCN Global Standard for reporting on NbS in NDCs for PSIDS.