The corrosion and adsorption behavior of leaf extract ofFuntumiaelastica(FE) on mild steel corrosion was studied in 1 M HCl using gravimetric ,electrochemical impedance spectroscopy, potentiodynamic polarization and Fourier transformed infrared spectroscopy methods, Quantum chemical calculations were performed to theoretically correlate the inhibition performance of the inhibitor with its electronic structural parameters. The gravimetric experiment revealed that the extract effectively inhibited the corrosion of mild steel even at a prolonged exposure time. The impedance and polarization results revealed that the extract inhibited both the cathodic and anodic partial reactions via the adsorption of the inhibitor on the metal/solution interface. The FTIR results revealed FE as an adsorption inhibitor. The calculated quantum chemical parameters associated with the molecular structure of FE confirmed its inhibiting efficacy.