Collagen is one of the most abundant structural proteins in the human body and has emerged as a highly valuable biomaterial for pharmaceutical and biomedical applications. This review provides a comprehensive overview of collagen, including its structure, physicochemical properties, advantages, limitations, and diverse therapeutic applications. The article discusses both natural and synthetic collagen sources and summarizes major extraction techniques such as acid hydrolysis, alkaline hydrolysis, salt solubilization, enzyme-assisted extraction, ultrasoundassisted extraction, and microwave-assisted extraction. Recent advances in synthetic collagen preparation, including solid-phase peptide synthesis, recombinant collagen technology, chemical ligation, and polymer modification strategies, are also highlighted. In addition, various collagenbased formulations such as nanoparticles, hydrogels, films, sponges, microneedle systems, and transdermal patches are described along with their preparation methods and biomedical significance. Particular emphasis is placed on the role of collagen in controlled drug delivery, wound healing, tissue engineering, regenerative medicine, and transdermal therapeutic systems. Owing to its excellent biocompatibility, biodegradability, low immunogenicity, and ability to support cell growth and tissue regeneration, collagen continues to be a promising material for advanced drug delivery and regenerative healthcare applications. Future developments in recombinant technology, nanotechnology, and three-dimensional bioprinting are expected to further expand the clinical potential of collagen-based biomaterials.