In this work, we presented DFT-based sensing of acetone ' using ' pristine and transition metal ( Ni, Pd & Pt)-embedded graphitic carbon nitride (gCN) and validated it experimentally. The theoretical calculations of adsorption energy, band structure, and density of state analysis confirm that Pd/gCN has superior sensing characteristics as compared to pristine gCN, Ni/gCN, and Pt/gCN. Further, the sensing response is calculated from the current-voltage characteristics using the simulated devices from optimized structures. In experimental part of the study, pristine gCN and Ni, Pd, and Pt-embedded gCN nanosheets are synthesized by thermal poly-condensation and chemical reduction method. The synthesized materials were characterized using UV/Vis, FTIR, XRD, HRTEM, FESEM, and EDS techniques which confirm the formation of all the materials. The sensing properties such as response, response/recovery times, selectivity, and stability are calculated. The experimental study also confirms that Pd/gCN is the best material for room temperature sensing of acetone, followed by Ni/gCN, Pt/gCN, and pristine gCN. The response of Pd/gCN for 20 ppm acetone at room temperature is 15%. The response/recovery times are 770.04/37.48 s. Moreover, the response of Pd/gCN is stable for ten days. Hence, the experimental finding is in line with the theoretical study.