This research investigates the inhibitory performance of BM-02, a synthesized pyrazole derivative (R)-5-(4-methoxyphenyl)-1,3-diphenyl-4,5-dihydro-1H-pyrazole, against the corrosion of mild steel in a 1 M hydrochloric acid solution. A comprehensive array of experimental techniques, including weight loss analysis, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy, were employed to assess the inhibitory effectiveness. BM-02 is identified as a mixed inhibitor, showcasing a remarkable efficiency of 91.5% at a concentration of 10−3 mol/l. The adsorption behavior of the BM-02 molecule was investigated, revealing a physical adsorption model in accordance with the Langmuir isotherm. Furthermore, ATR-IR, 1H NMR, and 13C NMR spectra were acquired, complemented by density functional theory (DFT) calculations and molecular dynamics (MD) simulations to gain deeper insights into the molecular interactions and corrosion inhibition mechanism.