The article reviews the emerging field of peptide-drug conjugates (PDCs) as a novel approach in cancer theranostics. PDCs utilize target-oriented peptides as carriers of cytotoxic payloads, connected by cleavable or noncleavable linkers, to enhance specificity and efficacy in targeted drug delivery. The review highlights the advantages of PDCs over traditional antibody-drug conjugates (ADCs), including better stability, reduced side effects, and enhanced penetration into cancer cells. Key aspects discussed include the design and chemistry of cell-targeting (CTPs) and cell-penetrating peptides (CPPs), the importance of linker chemistry, and the selection of cytotoxic payloads. The article also explores chemical modifications to improve peptide stability and bioavailability, such as cyclization, d-amino acids, and nanomicroformulations. Additionally, it covers the therapeutic mechanisms of PDCs, their clinical applications, and the challenges and future directions in the field. The review aims to provide a comprehensive overview of PDCs, emphasizing their potential as a promising therapeutic modality in cancer treatment.The article reviews the emerging field of peptide-drug conjugates (PDCs) as a novel approach in cancer theranostics. PDCs utilize target-oriented peptides as carriers of cytotoxic payloads, connected by cleavable or noncleavable linkers, to enhance specificity and efficacy in targeted drug delivery. The review highlights the advantages of PDCs over traditional antibody-drug conjugates (ADCs), including better stability, reduced side effects, and enhanced penetration into cancer cells. Key aspects discussed include the design and chemistry of cell-targeting (CTPs) and cell-penetrating peptides (CPPs), the importance of linker chemistry, and the selection of cytotoxic payloads. The article also explores chemical modifications to improve peptide stability and bioavailability, such as cyclization, d-amino acids, and nanomicroformulations. Additionally, it covers the therapeutic mechanisms of PDCs, their clinical applications, and the challenges and future directions in the field. The review aims to provide a comprehensive overview of PDCs, emphasizing their potential as a promising therapeutic modality in cancer treatment.