The presence of microplastics in marine environments poses a major ecological risk, particularly along densely populated coastal regions like the Sukolilo Baru Kenjeran Coast, Surabaya. Waste from sea catch processing industries represents a significant yet underexplored source of contamination. This research aims to identify the abundance, characteristics, and polymer composition of microplastics in sea catch waste (shrimp, sea cucumber, ball sea cucumber, fish, and shellfish) from the area. Waste samples were analyzed using a stereo microscope to characterize morphology (type, color, and size). The polymer composition of four types (n = 4 waste samples of shrimp waste, sea cucumber waste, fish waste, shellfish waste) of representative particles was identified using Attenuated Total Reflectance–Fourier Transform Infrared (ATR-FTIR) spectroscopy. Results indicated that all waste samples were contaminated with microplastics, with the highest abundance observed in shrimp waste (45 particles). Fibers were the most dominant morphology, suggesting a source from secondary microplastics. Two color distribution patterns were identified: shrimp and sea cucumber waste were dominated by black particles, whereas other waste types were dominated by blue. FTIR analysis identified two distinct polymer profiles, with shellfish waste exhibiting a unique chemical composition compared to other samples. These findings confirm that waste from sea catch processing serves as a direct pathway for microplastic entry into coastal aquatic environments. Therefore, improved waste management strategies are required to mitigate microplastic pollution originating from the fisheries sector.