The persistence of polyethylene (PE) plastics, particularly low-density (LDPE) and high-density polyethylene (HDPE), has become a major contributor to marine microplastic pollution due to their recalcitrant nature and slow degradation rate. This study aimed to identify and characterize marine bacterial isolates capable of degrading LDPE and HDPE under laboratory conditions. Sediment and seawater samples were collected from plastic-polluted coastal areas, and bacterial isolates were cultured on mineral basal medium supplemented with LDPE and HDPE powders as the sole carbon source. Biodegradation efficiency was evaluated through quantitative weight-loss analysis and qualitative assessment using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Among 16 isolates obtained, four exhibited notable degradation abilities. The isolates ALD3 and SHD showed the highest degradation rates for LDPE (17.42%) and HDPE (11.12%), respectively. SEM revealed substantial surface erosion and cracking, while FTIR confirmed the formation of carbonyl and hydroxyl functional groups, indicating oxidative degradation of the polyethylene chains. Molecular identification via 16S rRNA sequencing classified the most active isolates as Pseudoalteromonas sp. and Bacillus albus. These findings demonstrate that marine-derived bacteria possess promising enzymatic potential for polyethylene biodegradation and could serve as sustainable biocatalysts in mitigating marine microplastic pollution. Further studies focusing on enzyme characterization and optimization of environmental parameters are recommended to enhance biodegradation efficiency in natural marine ecosystems. These findings provide a foundation for developing enzyme-based bioreactors for in situ microplastic remediation in marine environments.