Abstarct: Nanostructured gas sensors have a high potential for detecting toxic and pollutant gases due to their large specific surface area, tunable surface properties, and controllable charge-transfer behavior. However, the performance of these sensors is strongly influenced by the synthesis method, fabrication conditions, and architecture of the sensing material. Using a review-baxsed analytical approach, the present study examines novel synthesis and structuring methods for nanomaterials used in gas sensors. Relevant scientific sources were selected, compared, and analyzed baxsed on the type of synthesis method, film-fabrication technique, structural characteristics, and sensing-performance indicators. In the section on chemical methods, processes such as hydrothermal synthesis, microwave-assisted hydrothermal synthesis, sol–gel processing, electrospinning, green synthesis, and strategies for fabricating nanocomposites were investigated. Thin-film fabrication methods, including magnetron sputtering, thermal and electron-beam evaporation, chemical vapor deposition, atomic laxyer deposition, solution-baxsed coating techniques, and glancing-angle deposition, were also analyzed. The reviewed studies indicated that parameters such as grain size, porosity, specific surface area, crystalline phase and exposed crystal facets, oxygen vacancies, film thickness, and interfacial quality are directly related to sensor sensitivity, selectivity, response and recovery times, operating temperature, and stability. It was also found that increasing the specific surface area or reducing particle size alone is insufficient to achieve optimal performance; these characteristics must be accompanied by suitable gas-diffusion pathways, effective electrical connectivity, and a controlled density of active sites. Doping, surface decoration, and the formation of heterojunctions can also improve sensor performance by regulating charge-carrier concentration and surface reactivity. Despite the progress achieved, challenges such as limited selectivity, humidity interference, high operating temperature, long-term instability, difficulties in achieving reproducibility, and limitations in scale-up still remain. Overall, the fabrication method should be selected by establishing a balance among sensing performance, cost, stability, and industrial manufacturability.