Chitosan seems to be an innovative biological material potentially utilized as a nanoparticle carrier for drug delivery, which could be low toxic, biocompatible, and easy to prepare. Chitosan nanoparticles have been employed in gene delivery. As a type of multifunctional adjuvant, chitosan nanoparticles could activate the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway to induce cell protection and/or proliferation via the modulation of autophagy within dendritic cells. In general, adjuvants may improve the innate and/or adaptive immune responses to a vaccine antigen by facilitating the antigen presentation of antigen presenting cells such as dendritic cells. The choice of a suitable adjuvant has become vital for improved safety and/or expanded application of vaccines. Fortunately, chitosan nanoparticles could be designed to target the dendritic cells to be enhanced by its adjuvant effect and for stimulating robust immune responses. Therefore, chitosan nanoparticles may be a good immune stimulant with encouraging properties for the development of superior vaccine delivery. Indeed, vaccines could play a key role in human health. In this review, we summarize the concept and/or recent progress in the field of chitosan nanoparticles, providing a valuable resource for investigating the molecular mechanisms of chitosan for the development of a greater vaccine.