The corrosion inhibition efficiency of newly synthesized 3,5-diaryl-4-amino-1,2,4-triazole derivatives was investigated for mild steel corrosion in 1.0 M HCl medium using weight loss quantum chemical calculations and Monte Carlo simulations. It was found that the studied compounds exhibit a very good performance as inhibitors for mild steel corrosion in 1.0 M HCl. The results show that the inhibition efficiency increases with decreasing temperature and increasing concentration of inhibitors. The kinetic parameters such as E a, ΔH a, and ΔS a were evaluated. It was found that the adsorption for these inhibitors on the mild surface obeys the Langmuir adsorption isotherm at all studied temperatures and the adsorption isotherm parameters (K ads, ΔG ads°, ΔH ads°, and ΔS ads°) were determined and discussed. The values of inhibition efficiency for all triazoles followed the order 3-APAT < 4-APAT < 4-DTAT < 4-MAT < 3,4-MAT. The 3,4-methoxyphenyl substituted triazole (3,4-MAT) exhibited the highest inhibition efficiency of 98.5% at concentration of 1 × 10–4 M. Quantum chemical calculations using the Density Functional Theory (DFT) were performed on the 3,5-diaryl-4-amino-1,2,4-triazole derivatives in an attempt to correlate the corrosion inhibition properties of these 1,2,4-triazole derivatives with their calculated quantum chemical parameters. Furthermore, Monte Carlo (MC) simulations were applied to search for the most stable configuration and adsorption energy for the interaction of inhibitors on Fe (110)/30 H2O interface. A good correlation was observed between the Monte Carlo calculations and experimentally inhibition efficiency data.