Transdermal drug delivery has emerged as a promising alternative to conventional drug delivery systems. The use of biopolymers in transdermal drug delivery systems have shown favourable results with the required safety profile. Chitosan is a naturally occurring polysaccharide originated from marine sources. It offers excellent biocompatible and biodegradable nature as pharmaceutical excipient. It is also widely employed in the biomedical field due to its favourable properties. The hydrogel forming ability in combination with controlled release of incorporated drugs have widened the scope of chitosan as transdermal drug carriers. The antimicrobial and wound healing ability of chitosan has also aided in its use as a transdermally applied material. Chitosan possesses easy fabrication techniques, compatibility with most of the pharmaceutical excipients and therapeutic agents have also promoted its use. It can be easily fabricated into different transdermal dosage forms, including gels, patches, microneedles etc. The better understanding of its chemical modifications and physicochemical properties can help to enhance the efficacy of chitosan-based transdermal formulations.