<p>The excellent chemical stability and hydrophobicity of polyimide (PI) make it an attractive candidate for high-performance flexible electronic applications. However, detailed studies of PI-passivated metal oxide thin-film transistors (MOTFTs) are still lacking. In this work, we fabricated indium oxide (In₂O₃) TFTs employing a PI passivation layer (PPL), which resulted in low damage and good dielectric quality. A comprehensive comparison of the electrical performance was conducted in terms of the saturation mobility, on/off current ratio (<i>I</i>_on/<i>I</i>_off), threshold voltage (<i>V</i>_th), subthreshold swing (<i>SS</i>), and interface trap density (<i>N</i>_it) of the In₂O₃ TFTs passivated with PI of different thicknesses. In addition, the PPL was found to significantly suppress the adsorption of surrounding moisture and oxygen from the environment owing to its most chemically robust carbon-fluorine bond. The TFT with PPL exhibited relatively good electrical performance (<i>μ</i>_sat = 2.418 cm²/Vs) compared with that (<i>μ</i>_sat = 1.2 cm²/Vs) of the TFT without the PPL. The passivated device exhibited good stability (Δ<i>V</i>_th: −0.95&#xa0;V), while the TFTs without the PPL showed a −8.0&#xa0;V Δ<i>V</i>_th shift. The results indicate that PI-passivated In₂O₃ TFT demonstrates a drastically reduced threshold voltage and highest stability. Consequently, PI film is a promising organic material for various emerging electronic devices.</p> Graphical abstract <p></p>