There are several uses for nanostructured gas sensors in environmental monitoring. Calcium oxide (Ca₁₂O₁₂) nanocages have significant surface area and unique structural characteristics, making them ideal for real-world sensing applications. Using dispersion-corrected density functional theory (DFT) computations, we examined the adsorption of carbon monoxide (CO), nitrogen oxide (NO), and hydrogen cyanide (HCN) gases on (Ca12O12) nanocages that are doped with transition metals (TM = Sc to Zn) and those that are pure. Charge transfer, as demonstrated by the analysis of dipole moments, adsorption energies, molecular electrostatic potential (MEP), thermodynamic characteristics (Gibbs free energy, ΔG, and enthalpy, ΔH), molecular dynamics (MD) simulations, non-covalent interaction (NCI), natural bonding orbitals (NBOs), and the quantum theory of atoms in molecules (QTAIM) were all considered. The ΔG values of all complexes, except for the NO/CuCa11O12, NO, and HCN on CoCa11O12, NO, CO, and HCN on ZnCa11O12 complexes, were negative, suggesting weak adsorption. For optimal geometries, the binding energy of TM-doped Ca11O12 falls between -5.728 and -6.023 eV. The CO, NO, and HCN adsorption energies in pure Ca12O12 nanocages are -0.404, -0.671, and -0.423 eV, respectively. On the other hand, the interaction energies for CO /TM-doped Ca11O12, ranged from -0.172 (Zn) to -2.616 (Cr) eV; for NO/TM-doped Ca11O12, ranged from -0.149 (Zn) to 4.072 (Cr); and for HCN/TM-doped Ca11O12, ranged from -0.055 (Zn) to -2.556 (Ti) eV, respectively. Ultimately, TM-doped Ca11O₁₂ nanocages have the potential to improve the accuracy and reliability of hazardous substances, such as HCN, NO, and CO, detection in next-generation sensor technologies.