Ternary two-dimensional metal oxide spinel's (A2BO4) have fascinated many researchers due to its inimitable properties such as large reactive surface area, unique phase structure, electrical conductivity, and morphology of the thin film surface. Limitations of a single metal oxide chemi-resistive gas sensor are its higher operating temperature, low detection limit, and long-term stability. In this investigation, a widely employed spray pyrolysis technique is used to deposit different thicknesses of Co2SnO4 thin films. As deposited and annealed films were subjected to all the necessary characterization such as structural, optical, topographical, morphological, and gas sensing performance to understand their performance in real-time application. The synergetic effects of high surface roughness, aggregated porous nanograin morphology, and various physio-chemical properties possibly prompt higher thickness film (A - Co2SnO4) to attain ultrahigh sensor response S = 6074 ± 43, and a good response/recovery time 155 ± 6 s and 44 ± 5 s at 3 ppm at 300 K, respectively. The thin film sensor has excellent long-term stability, repeatability, good moisture resistance, and the lowest detection limit (LOD) with a range of approximately 1 ppm and demonstrates discernible sensor response S = 690 ± 40. These results are the new pathway for tracing dimethylamine gas at room temperature. It can be easily used in food inspection sectors to monitor and detect food freshness.