Ophiocordyceps sinensis is one of the best-known traditional Chinese medicines with distribution confined to the Tibetan Plateau and its surrounding regions. Harvesting the fungus contributes greatly to the livelihood of local communities. The quality and price varies amongst different production regions, usually resulting in an intentional mix-up of its production locality during trading processes, which leads to a demand of developing a reliable way that can trace the geographical origin of this fungus. In the present study, a DNA barcoding-based method applying two universal DNA barcodes for identifying fungal and insect, respectively i.e. the nuclear ribosomal internal transcribed spacer (ITS) and the mitochondrial cytochrome oxidase I (COI), was evaluated and used for geographical origin authentication of O. sinensis. A total of 24 ITS and 78 COI haplotypes were recognised from 215 individuals collected from 75 different geographic localities (county level). Ninety-nine haplotypes were defined using the combination of ITS and COI, discriminating the 75 investigated production counties into 99 distinct regions. A “core” production region was recognised which covers areas of Nagqu and Qamdo in Xizang, Yushu and Guoluo in Qinghai, Gannan (Maqu and Xiahe) in Gansu and certain regions in Nyingch (Bomi and Zayü) and Lhasa (Damxung) in Xizang and Garzê (Sêrxü) in Sichuan Province. Haplotype analyses using the combined barcodes of ITS and COI showed an excellent performance in the geographical origin authentication of O. sinensis and the definition of “core” and “non-core” production region.