Transdermal drug delivery systems (TDDS) represent a clinically significant non-invasive route for systemic drug administration, offering distinct pharmacokinetic advantages over conventional oral and parenteral formulations. By delivering active pharmaceutical ingredients across the skin and into the systemic circulation, TDDS circumvents hepatic first-pass metabolism, reduces gastrointestinal adverse effects, and facilitates predictable, sustained plasma drug concentrations. This review aims to provide a concise yet comprehensive appraisal of contemporary advances in transdermal technologies, spanning conventional patch systems, microneedle-based delivery platforms, nanotechnology-driven carriers, and bioresponsive stimuli-sensitive systems. Major technological developments discussed include chemical and physical skin permeation enhancement strategies—such as iontophoresis, sonophoresis, and electroporation—as well as nanocarrier-mediated transport via liposomes, nanostructured lipid carriers (NLCs), transfersomes, and polymeric nanoparticles. Therapeutic applications encompassing pain management, hormonal therapy, cardiovascular pharmacology, neurological conditions, and transdermal vaccine delivery are critically evaluated. The review also identifies persistent clinical and regulatory challenges, including the inherent impermeability of the stratum corneum, constraints on drug physicochemical properties, skin sensitisation risks, and the regulatory complexity surrounding novel enhancement technologies. Emerging innovations such as dissolving microneedles, smart hydrogels, 3D-printed patches, and wearable biosensor-integrated delivery platforms are highlighted as transformative future directions. In conclusion, TDDS hold immense potential for expanding the repertoire of deliverable therapeutics and improving patient-centric outcomes across diverse clinical indications.