<p>Solution-processed indium-doped zinc oxide (IZO) is a particularly interesting semiconductor for its wide-bandgap, high carrier mobility, and compatibility with low-temperature fabrication on flexible substrates. Besides these advantages, sol–gel spin-coated IZO films commonly face critical issues associated with coffee-ring formation, pinholes, and limited crystallinity, severely degrading charge transport in the film. Herein, we present a dual strategy that incorporates ammonium acetate (AA) precursor modification and pre-O₂ plasma substrate treatment to achieve improvement in the structure, morphology, and electrical characteristics of sol–gel IZO films. The dual approach of AA incorporation and plasma activation synergistically transforms the substrate into a superhydrophilic state, decreasing the contact angle from 84° to 6.7° (≈&#xa0;92% reduction), thus notably improving precursor wetting and film adhesion. X-ray diffraction studies indicate increased crystallite size and reduced lattice strain in the film upon AA treatment. Field-emission scanning electron microscopy and atomic force microscopy confirm the suppression of coffee-ring patterns and pinholes toward nanoscale uniform grain coalescence. This is coupled with enhanced lattice oxygen bonding and a simultaneous reduction in hydroxyl-related surface defects as observed by X-ray photoelectron spectroscopy while preserving oxygen vacancy-related donor states that contribute to n-type conduction. Consequently, in the IZO films treated in this dual strategy, the Hall mobility enhanced fivefold from 3.75 to 18.5 cm²&#xa0;V⁻¹&#xa0;s⁻¹ and carrier concentration increased sixfold from 3.28 × 10¹⁷ to 2.11 × 10¹⁸&#xa0;cm⁻³ resulting in the 30-fold enhancement in the electrical conductivity. Overall, this work provides the first investigation of AA-assisted stabilization effects on the wettability, defect suppression, and electrical transport behavior of sol–gel-derived IZO thin films under a fixed processing condition.</p>