This work investigates a solution process for yttria-stabilized zirconia (YSZ) thin film deposition involving the addition of yttria nanoparticles, at 400 ○C, in air. Different yttrium doping levels in the YSZ were studied and a wide range of optical, structural, surface, dielectric, and electronic transport properties were also investigated. An optimum yttrium doping level of 5% mol. resulted in the smoothest films (RRMS ∼ 0.5 nm), a wide bandgap (∼5.96 eV), a dielectric constant in excess of 26, and a leakage current of ∼0.3 nA cm−2 at 2 MV/cm. The solution-processed YSZ films were incorporated as gate dielectrics in thin films transistors with solution-processed In2O3 semiconducting channels. Excellent operational characteristics, such as negligible hysteresis, low operational voltages (5 V), electron mobility in excess of 36 cm2 V−1 s−1, high on/off current modulation ratio on the order of 107, and low interfacial trap density states (<1012 cm−2), were demonstrated. In addition, excellent film homogeneity was achieved over a large area (16 × 16 cm2), with both film thickness and capacitance deviation of <1.2%.