Purpose: This study aimed to investigate the presence, morpho-polymer characteristics, and potential ecological impacts of microplastics (MPs) in sediment samples from two popular tourist beaches along the northern Bay of Bengal. MP contamination is a rising issue in Bangladesh coastal waters, given its dense population, extensive plastic manufacturing, and a lack of waste processing facilities. Materials and methods: Sediment samples were collected from two tourist beaches. Microplastics were identified, quantified, and categorized by type, size, shape, and color. Statistical analyses were performed to compare microplastic abundance between the two sites. Polymer composition was analyzed using Fourier-transform infrared spectroscopy (FTIR). Multivariate analyses were used to identify potential sources of contamination. Results and discussion: Microplastic abundance ranged from 55.83 ± 10.10 to 116.67 ± 11.27 items kg⁻¹ at Patenga beach and 60.00 ± 6.61 to 135.83 ± 12.58 items kg⁻¹ at Parki beach. Fibers dominated Patenga beach (68.71%), while foam was prevalent at Parki beach (48.97%). Most microplastics were < 0.5 mm, filamentous, and transparent (Patenga) or white (Parki). Polyethylene (33.33%) was the most common polymer. Morpho-polymer characteristics and statistical analyses indicated the sources of MPs were linked to tourism, industrial waste, river discharge, and fishing activities. Conclusions: This study revealed moderate microplastic pollution at the study beaches, offering baseline data for the northeastern Bay of Bengal. The findings highlighted that targeted waste management policies are urgently needed to reduce coastal microplastic contamination.