This review provides an overview of chitosan-based nanoparticles (NPs) for non-parenteral drug delivery, focusing on their properties, modifications, and applications in various therapeutic areas. Chitosan, a biodegradable and biocompatible polymer derived from chitin, is widely used in drug delivery due to its mucoadhesive properties, positive surface charge, and ability to modify for specific applications. Chitosan NPs can be tailored for sustained release, mucoadhesion, and targeted delivery to various tissues, including the gastrointestinal tract, lungs, brain, and ocular systems. The review highlights the use of chitosan in oral, nasal, pulmonary, and vaginal drug delivery, emphasizing its ability to enhance drug absorption and bioavailability by improving permeability and reducing first-pass metabolism. Chitosan NPs have been shown to be effective in delivering drugs such as insulin, anti-cancer agents, and anti-inflammatory compounds. The review also discusses the pharmacokinetics of chitosan-based formulations, demonstrating improved drug absorption and retention in vivo. Toxicity studies indicate that chitosan is generally safe, with minimal adverse effects. The review outlines various methods for preparing chitosan NPs, including ionotropic gelation, complex coacervation, coprecipitation, microemulsion, and emulsification solvent diffusion. These methods allow for the controlled synthesis of NPs with desired properties for specific therapeutic applications. Overall, chitosan-based NPs offer a promising platform for non-invasive drug delivery with potential for improved therapeutic outcomes.This review provides an overview of chitosan-based nanoparticles (NPs) for non-parenteral drug delivery, focusing on their properties, modifications, and applications in various therapeutic areas. Chitosan, a biodegradable and biocompatible polymer derived from chitin, is widely used in drug delivery due to its mucoadhesive properties, positive surface charge, and ability to modify for specific applications. Chitosan NPs can be tailored for sustained release, mucoadhesion, and targeted delivery to various tissues, including the gastrointestinal tract, lungs, brain, and ocular systems. The review highlights the use of chitosan in oral, nasal, pulmonary, and vaginal drug delivery, emphasizing its ability to enhance drug absorption and bioavailability by improving permeability and reducing first-pass metabolism. Chitosan NPs have been shown to be effective in delivering drugs such as insulin, anti-cancer agents, and anti-inflammatory compounds. The review also discusses the pharmacokinetics of chitosan-based formulations, demonstrating improved drug absorption and retention in vivo. Toxicity studies indicate that chitosan is generally safe, with minimal adverse effects. The review outlines various methods for preparing chitosan NPs, including ionotropic gelation, complex coacervation, coprecipitation, microemulsion, and emulsification solvent diffusion. These methods allow for the controlled synthesis of NPs with desired properties for specific therapeutic applications. Overall, chitosan-based NPs offer a promising platform for non-invasive drug delivery with potential for improved therapeutic outcomes.