We fabricated Zn-Sn-O (ZTO)-based oxide and In-Zn-O (IZO) stacked channel thin-film transistors (TFTs) by experimentally using ultraviolet (UV) annealing for activation. The field-effect mobility was about 30 cm²/Vs, and the threshold voltage (V_th) was–3.5 V at the UV annealing temperature of 200°C. These TFTs improved the reliability of the negative gate bias illumination stress (NBIS) test more than the In-Ga-Zn-O (IGZO) TFTs did. The ZTO/IZO stacked channel TFTs are promising candidates for next-generation flexible devices.