The surface activity and molecular self-assembly influence their impact on various systems due to unique properties of surfactants. Nonionic surfactants are amphiphilic molecules that play a crucial role in pharmaceutical formulations due to their unique physicochemical properties and biocompatibility. Their low toxicity, chemical stability, and ability to form micelles and other self-assembled structures have made them highly valuable in enhancing the solubility and bioavailability of poorly water-soluble drugs. The functional properties of ionic or nonionic surfactants such as hydrophilic-lipophilic balance (HLB), critical micelle concentration (CMC), viscosity modulation, and interfacial tension reduction are key factors in their performance within drug delivery systems. These surfactants exhibit strong solubilizing capacity and can encapsulate both hydrophobic and hydrophilic drugs, protecting them from degradation and enabling controlled or targeted release. A prominent application of nonionic surfactants is in the formation of niosomes, vesicular carriers composed of nonionic surfactant bilayers. These systems offer targeted delivery, reduced side effects and enhanced therapeutic efficacy. This chapter explores the fundamental properties of nonionic surfactants and highlights their roles in various drug delivery applications. The chapter also describes all aspects of niosomes (nonionic surfactants) including their different composition, properties and function for drug delivery.