This review discusses the applications and findings of cyclodextrins (CDs) and their derivatives in various areas of drug delivery, particularly in protein and peptide drug delivery and gene delivery. CDs, with their lipophilic inner cavities and hydrophilic outer surfaces, can form noncovalent inclusion complexes with a wide range of guest molecules. The article highlights the use of CDs in designing novel delivery systems such as liposomes, microspheres, microcapsules, and nanoparticles. It also covers the effects of CDs on drug solubility, dissolution, bioavailability, safety, and stability, as well as their use as excipients in drug formulation. The review discusses factors influencing inclusion complex formation, including the type of CD, cavity size, charge, temperature, and preparation methods. It also addresses commercial availability, regulatory status, and patent status of CDs and their derivatives. The article further explores the effects of CDs on drug properties, such as solubility, dissolution, bioavailability, safety, and stability, and their applications in oral, parenteral, ocular, nasal, and rectal drug delivery. CDs are found to enhance drug solubility, reduce irritation, improve permeability, and stabilize drugs, making them valuable in various drug delivery systems.This review discusses the applications and findings of cyclodextrins (CDs) and their derivatives in various areas of drug delivery, particularly in protein and peptide drug delivery and gene delivery. CDs, with their lipophilic inner cavities and hydrophilic outer surfaces, can form noncovalent inclusion complexes with a wide range of guest molecules. The article highlights the use of CDs in designing novel delivery systems such as liposomes, microspheres, microcapsules, and nanoparticles. It also covers the effects of CDs on drug solubility, dissolution, bioavailability, safety, and stability, as well as their use as excipients in drug formulation. The review discusses factors influencing inclusion complex formation, including the type of CD, cavity size, charge, temperature, and preparation methods. It also addresses commercial availability, regulatory status, and patent status of CDs and their derivatives. The article further explores the effects of CDs on drug properties, such as solubility, dissolution, bioavailability, safety, and stability, and their applications in oral, parenteral, ocular, nasal, and rectal drug delivery. CDs are found to enhance drug solubility, reduce irritation, improve permeability, and stabilize drugs, making them valuable in various drug delivery systems.