Many new therapies are currently being used to treat cancer. Among these, chemotherapy based on peptides has been of great interest due to the unique advantages of peptides, such as a low molecular weight, the ability to specifically target tumor cells, and low toxicity in normal tissues. In treating cancer, peptide-based chemotherapy can be mainly divided into three types, peptide-alone therapy, peptide vaccines, and peptide-conjugated nanomaterials. Peptide-based vaccines have been used in advanced cancers to improve patients overall survival. The combination of peptides with nanomaterials expands the therapeutic ability of peptides to treat cancer by enhancing drug delivery and sensitivity. Immune recognition and elimination of cancerous cells is the primary goal of cancer immunotherapy. However, obstacles including immune tolerance and tumor-induced immunosuppression often limit beneficial immune responses. Vaccination is one proposed intervention that may help to overcome these issues and is an active area of study in cancer immunotherapy. Immunizing with tumor antigenic peptides is a promising, vaccine strategy hypothesized to boost pre-existing antitumor immunity. However, tumor antigens are often weak T cell agonists, attributable to several mechanisms, including immune self-tolerance and poor immunogenicity of self-derived tumor peptides. One strategy for overcoming these mechanisms is vaccination with mimotopes, which alter the antigen presentation and/or T cell activation. Peptide vaccines incorporate one or more short or long amino acid sequences as tumor antigens, combined with a vaccine adjuvant. Thus, they fall broadly into the category of defined-antigen vaccines, along with vaccines using protein, protein subunits, DNA, or RNA.