Transparent conducting oxides (TCOs) have both the electrical conductivity of a metal and the optical transparency of an insulator. Due to this unique feature, TCO is utilized in various applications such as flat panel displays, solar cells, light emitting diodes, and smart windows. At present, Sn-doped In₂O₃ (ITO) is the most widely used in the TCO market because of the superior materials properties. However, due to the demand for higher conductivity, instability of indium supply and high price, research to find new TCO materials has been continuously conducted. In this study, to develop a new TCO based on ZnO, we investigate the thermal stability of the transition metal dopants Sc and V and their effect on the band structure of ZnO using first-principles calculations. Our results show that Sc and V are efficient donors that can generate one free electron by substituting Zn when doped into ZnO. Furthermore, by analyzing the band structure of the doped system and calculating the electron effective mass, we show that Sc and V doping can be an important strategy to develop ZnO-based high-performance TCOs.