This study evaluated microplastic pollution in beach sand from three urban beaches in Tamil Nadu, India, namely Marina, Edward Elliot’s and Kovalam beach by comparing abundance, polymer types, shapes, sizes and surface weathering across four beach zones (low tide, intertidal, high tide and backshore) and three anthropogenic intensity levels (low, moderate, high). Overall MP concentrations increase from 50 ± 33 MP kg⁻¹ in the low‑tide zone to 463 ± 213 MP kg⁻¹ in the backshore. Beaches with high anthropogenic zone (361 ± 262 MP kg⁻¹) contained more MPs than moderate (250 ± 169 MP kg⁻¹) or low anthropogenic zone (187 ± 157 MP kg⁻¹). Among the site, Marina Beach (415 ± 254 MP kg⁻¹) was the most polluted, followed by Edward Elliot’s (214 ± 155 MP kg⁻¹) and Kovalam (170 ± 121 MP kg⁻¹). Polyethylene (47%), polypropylene (24%), polyamide (19%) and polystyrene (8%) dominated the polymer profile. Fibers were the most abundant shape, and 0.1–1 mm MP particles accounted for 41% of the total MPs. SEM imaging revealed surface abrasion, cracking, pitting and pore formation, indicating advanced weathering. These patterns point to recreational, tourism and fishing activities as primary MP sources. To safeguard coastal ecosystems, implementation of robust, long‑term waste‑management practices is urgently required.