Taraxasterol and ψ-taraxasterol are pentacyclic triterpenoids, they are commonly found in the family Asteraceae. These two compounds are useful candidates for pharmacologically active triterpenes in dandelion. A multifunctional oxidosqualene cyclase (TcOSC1) of Taraxacum coreanum catalyzes the cyclization of 2,3-oxidosqualene into various triterpenes (taraxasterol, ψ-taraxasterol, δ-amyrin, β-amyrin, α-amyrin, and dammarendiol-II). Here, we established the production of taraxasterol, ψ-taraxasterol, δ-amyrin, β-amyrin, and α-amyrin in transgenic tobacco overexpressing TcOSC1 gene of T. coreanum. Transgenic tobacco overexpressing TcOSC1 gene was induced via Agrobacterium-mediated transformation, and four transgenic lines were selected. Introduction and expression of transgenic genes in tobacco was confirmed by genomic PCR, and qRT-PCR, respectively. All the four transgenic lines of tobacco produced obviously the five triterpenes, namely taraxasterol, ψ-taraxasterol, δ-amyrin, β-amyrin, and α-amyrin. Organ-specific triterpene accumulation occurred in transgenic tobacco plants (leaf > stem > root). The amount of taraxasterol was found the highest among the five triterpenes produced in tobacco. The total amount of triterpenes in transgenic line 3 (Tr3) exhibiting the highest amount of triterpenes that was 598 µg g− 1 dry weight. Production of phytosterols (β-sitosterol, campesterol, and stigmasterol) was reduced in transgenic tobacco compared to those of wild-type control. Conclusively, we successfully established the production of taraxasterol and ψ-taraxasterol triterpenes in transgenic tobacco, which can be applied to the cost-effective production for the utilization and as a source of pharmacologically active materials.