Reactive oxygen species (ROS) are highly reactive molecules that, when produced in excess, contribute to oxidative stress, promoting cellular damage and the progression of various diseases, including cancer. Polydatin (PD) is known for its antioxidant, anti-inflammatory, and pro-apoptotic properties, proving effective in several in vitro studies as an antitumor agent. However, its clinical application is limited by low bioavailability, poor water solubility, and chemical instability. To overcome these limitations, nanocarrier systems based on biopolymers, such as chitosan (CS), represent promising strategies for drug delivery. In this study, we developed and optimized CS nanocapsules loaded with Polydatin using the ionotropic gelation method. The final formulation was characterized by UV-Vis spectrophotometry, scanning electron microscopy (SEM), and dynamic and dielectrophoretic light scattering (DLS, DELS). Encapsulation efficiency (EE) and the biological effects of the nanocapsules on cancer cells were also evaluated. To assess their antitumor potential, PD-CS nanoparticles were tested on the human breast cancer SKBR3 cells, analyzing their effects on cell viability. The results demonstrate that CS nanocapsules loaded with PD are able to reduce SKBR3 cell proliferation, highlighting their potential for developing new therapeutic tools for cancer treatment.