Photodynamic therapy (PDT) is a highly controllable and effective therapeutic strategy that does not cause drug resistance. Precise delivery of photosensitizers to tumor lesions can optimize therapeutic outcomes. Peptides, as alternatives to protein antibodies, have been applied as targeting ligands for biomedical imaging, drug delivery, and PDT. The article provides an overview of PDT and peptide-based nanosystems, detailing the structure, properties, and architecture of peptides. It highlights recent advances in peptide-based nanosystems for PDT, categorized by their functionalities: targeted, stimuli-responsive, self-assembled, and therapeutic. The design and development principles of these systems are discussed, emphasizing their potential in cancer treatment. Examples of peptide-based nanosystems, including their structure-property relationships and applications, are provided to offer insights and references for future research.Photodynamic therapy (PDT) is a highly controllable and effective therapeutic strategy that does not cause drug resistance. Precise delivery of photosensitizers to tumor lesions can optimize therapeutic outcomes. Peptides, as alternatives to protein antibodies, have been applied as targeting ligands for biomedical imaging, drug delivery, and PDT. The article provides an overview of PDT and peptide-based nanosystems, detailing the structure, properties, and architecture of peptides. It highlights recent advances in peptide-based nanosystems for PDT, categorized by their functionalities: targeted, stimuli-responsive, self-assembled, and therapeutic. The design and development principles of these systems are discussed, emphasizing their potential in cancer treatment. Examples of peptide-based nanosystems, including their structure-property relationships and applications, are provided to offer insights and references for future research.