<p>In a significant development for environmental monitoring, a novel CMC/GO/ZnO nanocomposite has been created that redefines the effectiveness of CO₂ gas sensing by fusing outstanding laser surface engineering with density functional theory (DFT)-based molecular modeling. The CMC/GO/ZnO composite (ZnO nanoparticles [ZnO-NPs) was created by combining carboxymethyl cellulose (CMC) with graphene oxide (GO) and nano-zinc oxide. DFT at the B3LYP/LANL2DZ level was used for modeling in order to investigate its electrical properties. The surface of this composite exhibited activity in terms of both molecular electrostatic potential (MESP) and density of states (DOS), as well as projected density of states (PDOS), which designates this composite as suitable for gas sensing. For experimental validation, the CMC/GO/ZnO-NPs were synthesized using the casting technique and subsequently characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopy. Various characterization methods confirmed the formation of the composite, which was then evaluated as a sensor for carbon dioxide (CO₂). The gas was tested in a handmade chamber, and the data obtained indicated that, at a constant operating temperature, the sensor response increased with prolonged working time. It can be concluded that the CMC/GO/ZnO-NPs sensor exhibited a rapid response to CO₂ gas, achieving a maximum response time of 60&#xa0;s. Further improvements in the performance of the sensor were observed when the CMC/GO/ZnO-NPs were subjected to laser irradiation. It was found that the laser modified the surface characteristics, which increased the interaction of the surface with the sensing gas. Laser exposure for 1 min showed a notable impact. The response and recovery times remained constant at roughly 6 s despite this improvement.</p>