This research explores an environmentally friendly alternative: lichens, which produce natural compounds with antioxidant effects. This study focuses on the inhibition of corrosion by lichens, which has not been previously explored for this purpose. The anti-corrosion potential of methanol extracts of Parmotrema hypoleucinum, Roccella phycopsis, and Xanthoria parietina was examined. The electrochemical impedance and weight loss methods were used to examine the corrosion inhibition process of mild steel XC48 in 1 M HCl by three lichen extracts.