The corrosion mitigation efficiency of Biotin drug for mild steel in 15% HCl was thoroughly investigated by weight loss and electrochemical methods. The surface morphology was studied by Contact angle, Scanning electrochemical microscopy (SECM), Atomic force microscope (AFM) and Scanning electron microscopy (SEM) methods. Quantum chemical calculation and Fukui analysis was done to correlate the experimental and theoretical data. The influence of concentration of inhibitor, immersion time, temperature, with activation energy, enthalpy and entropy has been reported. The mitigation efficiency of Biotin obtained by all methods was in good correlation with each other. Polarization studies revealed that Biotin acted as mixed inhibitor. The adsorption of Biotin was found to obey the Langmuir adsorption isotherm. Surface studies showed the hydrophobic nature of the steel with inhibitor and vindicated the formation of a film on the metal surface that reduced the corrosion rate.