<p>Polymeric and bio-based coatings have emerged as sustainable solutions for enhancing surface protection, durability, and functionality in advanced material systems. This review critically analyzes modern coating technologies by classifying them according to material type, deposition technique, functional role, and technology readiness. Key performance and sustainability trade-offs among metallic, ceramic, polymeric, and composite coatings are evaluated in relation to their structural, mechanical, and environmental properties.</p><p>Special emphasis is placed on the integration of bio-based polymers in biodegradable and recyclable coatings, with insights into recent advances in self-healing, antimicrobial, and smart responsive systems. Characterization methods, including SEM, XRD, FTIR, and nanoindentation, are discussed in relation to targeted application requirements and testing standards. The review concludes by outlining unresolved challenges and future directions for scaling sustainable coatings, particularly in the context of additive manufacturing, smart systems, and environmental regulations.</p> Graphical Abstract <p></p>