The article provides an overview of advancements and future prospects in peptide-based drug delivery systems (DDSs). Peptides, due to their high affinity, low immunogenicity, and adjustable molecular size, are widely used to couple with drugs to form peptide-drug conjugates (PDCs), which improve drug bio-compatibility and physiological stability. PDCs are particularly useful for delivering therapeutic substances like anti-cancer drugs and nucleic acid-based drugs, enhancing their concentration at the target site and prolonging their half-life in vivo. The article highlights the role of cell-targeted peptides (CTPs) in DDSs, which bind specifically to receptors highly expressed in specific cells or tissues, improving therapeutic efficacy and reducing toxic side effects. CTPs can target various receptors, including integrin receptors, CD13, epidermal growth factor receptor (EGFR), and extracellular matrix (ECM) receptors, facilitating drug delivery to the therapeutic site. Cell-penetrating peptides (CPPs) are another key component in peptide-based DDSs, capable of crossing cell membranes without disrupting their integrity. CPPs can enter cells through direct pathways, such as disrupting membrane stability, or via endocytosis, which is an energy-dependent process involving macropinocytosis, caveolin-mediated endocytosis, and clathrin-mediated endocytosis. The article also discusses the application of peptide-based DDSs in various diseases, including cancer, and their potential in clinical treatments. Peptide-based DDSs have shown promise in improving drug delivery efficiency, reducing toxicity, and enhancing therapeutic outcomes. Additionally, the article explores the use of peptide-based DDSs in imaging techniques like magnetic resonance imaging (MRI), chemical exchange saturation transfer imaging (CEST), and fluorescence imaging (FI), as well as in positron emission tomography (PET) for targeted drug delivery. Overall, the article emphasizes the importance of functional peptides in DDSs and their potential to revolutionize drug delivery systems, offering a more precise and effective approach to treating diseases.The article provides an overview of advancements and future prospects in peptide-based drug delivery systems (DDSs). Peptides, due to their high affinity, low immunogenicity, and adjustable molecular size, are widely used to couple with drugs to form peptide-drug conjugates (PDCs), which improve drug bio-compatibility and physiological stability. PDCs are particularly useful for delivering therapeutic substances like anti-cancer drugs and nucleic acid-based drugs, enhancing their concentration at the target site and prolonging their half-life in vivo. The article highlights the role of cell-targeted peptides (CTPs) in DDSs, which bind specifically to receptors highly expressed in specific cells or tissues, improving therapeutic efficacy and reducing toxic side effects. CTPs can target various receptors, including integrin receptors, CD13, epidermal growth factor receptor (EGFR), and extracellular matrix (ECM) receptors, facilitating drug delivery to the therapeutic site. Cell-penetrating peptides (CPPs) are another key component in peptide-based DDSs, capable of crossing cell membranes without disrupting their integrity. CPPs can enter cells through direct pathways, such as disrupting membrane stability, or via endocytosis, which is an energy-dependent process involving macropinocytosis, caveolin-mediated endocytosis, and clathrin-mediated endocytosis. The article also discusses the application of peptide-based DDSs in various diseases, including cancer, and their potential in clinical treatments. Peptide-based DDSs have shown promise in improving drug delivery efficiency, reducing toxicity, and enhancing therapeutic outcomes. Additionally, the article explores the use of peptide-based DDSs in imaging techniques like magnetic resonance imaging (MRI), chemical exchange saturation transfer imaging (CEST), and fluorescence imaging (FI), as well as in positron emission tomography (PET) for targeted drug delivery. Overall, the article emphasizes the importance of functional peptides in DDSs and their potential to revolutionize drug delivery systems, offering a more precise and effective approach to treating diseases.