The presence of plastic waste in waters, both in macro and micro forms, has been a widely researched topic in various studies at different observation sites. This underlies the need to study the spatial distribution of microplastics in the sediments of the Belawan estuary. In addition to the fact that no research has been conducted on microplastics in this area before, this study can provide up-to-date information and further analysis on the presence and abundance of microplastics in the sediments of the Belawan Estuary area. The purpose of this study is to determine the characteristics and distribution of microplastics in the sediments of the Belawan Estuary, North Sumatra. The research was conducted from September to December 2023. Microplastics in the sediments, obtained from 36 samples from aquatic sediments/sea floor and mangrove forest sediments, were found contain several types of microplastics, including fibers, fragments, foam, pellets, and films. Fragments and films were the most commonly found types of microplastics in the sediments of the Belawan estuary. Microplastics in mangrove sediments were found higher compared to aquatic sediments. The types of microplastic polymers found in the sediments of the Belawan estuary were Nylon, polyester (PES), polypropylene (PP), polystyrene (PS), and polytetrafluoroethylene (PTFE).