In this study, Allium Jesdianum extract (AJE) as a green banner for mild steel in 1 M HCl solution was appraised by some corrosion tests. The maximum inhibition efficiency about 96.18% was achieved by electrochemical impedance spectroscopy. The prominent declines of corrosion current density in both cathodic and anodic branches, as well as mixed-type inhibition, were confirmed by the potentiodynamic polarization technique. According to weight loss measurement, inhibition performance is dependent on AJE concentration. The adsorption of banner on the metal surface followed the Langmuir adsorption isotherm. Surface morphology and characterization methods were used to prove the inhibition mechanism.