Polyethylene oxide (PEO) is a multifaceted polymer with extensive applications in pharmaceutical product development. This review highlights its significant roles in various drug delivery systems. In hydrogels, PEO’s hydrophilicity and gel-forming capabilities enhance drug stability and controlled release. Osmotic pumps benefit from PEO’s ability to regulate osmotic pressure and drug solubility, ensuring precise and consistent drug delivery. PEO’s mucoadhesive properties improve drug retention and bioavailability in mucoadhesive drug delivery systems, providing sustained therapeutic effects. In gastro-retentive drug delivery systems, PEO prolongs gastric residence time, enhancing the bioavailability of drugs absorbed primarily in the stomach. Finally, PEO’s thermoplastic properties make it an essential component in hot melt extrusion processes, facilitating the formation of homogenous drug-polymer matrices and improving the solubility of poorly water-soluble drugs. Overall, PEO’s versatility and effectiveness across these applications underscore its critical role in advancing pharmaceutical formulations and optimizing therapeutic