Purpose Corrosion inhibitors most commonly are used in the acid pickling, cleaning and etching solutions. Plant extracts as rich and cheap resources are among the eco-friendly inhibitors. This study aims to investigate the inhibition effect of plantain extract on mild steel corrosion. Design/methodology/approach The inhibition influence of plantain extract on mild steel corrosion was investigated through Tafel polarization, electrochemical impedance spectroscopy and weight loss techniques in 1 M HCl solution. Furthermore, the sample surface morphology was verified by scanning electron microscopy. Findings The inhibition effect of the plantain extract was increased with the increase in the inhibitor concentration due to its adsorption on the surface of samples. The adsorption mechanism of the plantain extract on mild steel is physical adsorption and follows Langmuir isotherm. Originality/value The results obtained from different methods showed that the plantain extract has good inhibition performance on corrosion mild steel in 1 M HCl solution as a green inhibitor.