Evernia prunastri (lichen), a novel, eco-friendly, cost-effective, wide availability, safe, renewable and easy collection biosorbent, has been utilized for the removal of Safranin O (SO) dye from an aqueous solution. The biosorption behavior of SO onto the lichen biomass was investigated concerning parameters such as initial SO concentration (10–2000 mg L−1), solution pH (2.0– 12.0), lichen biomass dosage (1–20 g L−1), contact time (2–1440 min), temperature (5 °C, 25 °C, and 40 °C), and recovery were investigated. The zeta potential analyses showed that electrostatic attraction existed during the biosorption process between the SO and lichen biomass. The maximum SO biosorption capacity of the lichen biomass was 0.257 mol kg−1 at pH 6.0 and 25 °C. The biosorption energy for SO onto the lichen biomass was found to be EDR:8.9 kJ mol−1 reveals the biosorption proceeds chemically. The biosorption process follows the pseudo-second order and intra particle diffusion rate kinetics. Thermodynamic studies showed that SO biosorption, by this the lichen biomass is possible, spontaneous, and endothermic. Keywords: Lichen . Evernia prunastri . Biosorption . Cationic dye . SafraninO.