Colorectal cancer (CRC) is considered a lethal cancer all around the world, and its incidence has been reported to be increasing. Chemotherapeutic drugs commonly used for treating this cancer have shown some drawbacks, including toxicity to healthy cells and non-precise delivery. Thus, there is a necessity for discovering novel diagnostic and therapeutic options to increase the survival rate of CRC patients. Chitosan, as a natural polymer, has attracted a lot attention during the past years in different fields, including cancer. Studies have indicated that chitosan-based materials play various roles in prevention, diagnosis, and treatment of cancers. Chitosan nanoparticles (NPs) have been shown to serve as anti-cancer agents, which provide sustained drug release and targeted delivery of drugs to the tumor site. In this paper, we review available literature on the roles of chitosan in CRC. We discuss the applications of chitosan in designing drug delivery systems as well as anti-cancer activities of chitosan and involved signaling pathways.