Chitosan nanoparticles (NPs) have garnered significant interest in cancer therapy due to their unique properties, including biodegradability, biocompatibility, and mucoadhesive characteristics. This chapter provides a comprehensive overview of the applications of chitosan NPs in tumor-specific targeted drug delivery, emphasizing both passive and active delivery systems. Passive drug delivery systems utilize the enhanced permeability and retention (EPR) effect to accumulate chitosan NPs in tumor tissues, while active drug delivery systems utilize ligand-receptor interactions to enhance targeting specificity. The chapter delves into various strategies for active drug delivery using chitosan NPs, including folic acid-based, nucleic acid-based, peptide-based, and antibody-based targeting. Additionally, the chapter discusses the applications of chitosan NPs in different cancer categories, such as breast cancer, prostate cancer, lung cancer, colon cancer, and other malignancies like bladder cancer and gliomas. These discussions underscore the versatility of chitosan NPs in encapsulating a wide range of therapeutic agents and delivering them with increased precision to tumor sites, resulting in improved treatment outcomes and reduced systemic toxicity.