 This review provides an overview of the use of chitosan-based nanoparticles in various nonparenteral applications for drug delivery through different routes of administration, highlighting their sustained release and mucoadhesive properties. Chitosan is a biodegradable, biocompatible polymer with a tremendous range of potential applications due to its chemical functional groups that can be modified to achieve specific goals. The review explores recent research on chitosan-based NP for nonparenteral drug delivery, including their toxicity, pharmacokinetics, and pre-clinical studies.