Most flexible thin-film transistors employ plastic substrates instead of glass substrates, increasing white pollution. In this study, the flexible substrate is degradable nanocellulose paper, which has excellent smoothness with a roughness of only 3.12 nm that only increases to 6.03 nm after fabricating the entire device. Notably, the active layer of the paper-based thin-film transistors prepared using magnetron sputtering is IGZO/Al₂O₃. Therefore, the device can be fabricated at room temperature without undergoing thermal annealing, overcoming the limitation of nanopaper’s inability to withstand high temperatures. Al₂O₃ acts as an electronic bridge in the active layer, connecting the discontinuous indium gallium zinc oxide (IGZO). Furthermore, because IGZO is weakly crystalline, numerous carriers can circulate along the channel. The paper-based device exhibits excellent performance with a mobility of 22.5 cm²/(V·s), an on-off ratio of 5.07 × 10⁶, and a threshold voltage V_th of -0.036 V as well as good stability at positive and negative bias voltages. This paper-based thin-film transistor has great potential for applications in the green and flexible display industry.