<p>In the recent past, the development of sensors for harmful gas sensing has been in great demand. Hence, herein, the (0, 1, 2, 3, 4, &amp; 5 wt.%) Yttrium(III)-doped CeO₂ thin films were synthesized using the Nebulizer-assisted spray pyrolysis method for ammonia gas sensing applications. The films exhibited a polycrystalline structure with a cubic phase and a porous morphology, indicating homogeneous crystallization. The surface roughness of the films were increased with Yttrium doping concentration, attributed to the incorporation of Yttrium ions into the Ce sites of CeO₂. UV-Vis-NIR spectroscopy revealed an enhanced absorption in the red region, suggesting the presence of free electrons, which are beneficial for gas sensing. The Yttrium-doped CeO₂ films showed a reduced band gap, thus enhancing their suitability for gas sensing applications. Photoluminescence studies confirmed the presence of free electrons with a sharp blue emission peak at 478 nm, suggesting its application as blue LED. Gas sensing tests demonstrated an increased current value with higher NH₃ concentrations, with the 3% Y-doped CeO₂ thin film showing the best performance. Repeatability tests confirmed a stable gas response over 15 cycles at 250 ppm NH₃, ensuring the reliability and long-term stability of the 3% Yttrium-doped CeO₂ thin film as an effective and durable gas sensing material for industrial applications.</p> Graphical Abstract <p></p>