The present research work involves studies of the physical chemistry behind silk dyeing using the natural colourant extracted from lichen Parmotrema perlatum. The dye was extracted using an environmentally benign Ammonia Fermentation Method that consists of acetylshikonin and the methyl ester of nogalonic acid. A comprehensive kinetic and thermodynamic studies were undertaken to elucidate the adsorption behaviour of the extracted dye on silk fibre. Experimental procedures were conducted at various combinations of time (15, 30, 45, 60, 75, and 90 min) and temperature (50, 60, 70, 80, and 90 °C). The variation in dye concentration was monitored using a UV–visible spectrophotometer at 577 nm. Multiple kinetic models, like Lagergren, Intra-particle diffusion, and Elovich models, were applied to interpret the adsorption mechanism involved in the process. Physicochemical parameters affecting the dyeing process were expressed in terms of the activation energy, enthalpy, and change in entropy. The results demonstrate that the dyeing process is exothermic and follows a chemisorption mechanism. Furthermore, the Molecular docking outcomes suggest formation of stable hydrophobic and hydrogen bonds between dye-fibre molecules. Such findings corroborate each other and affirm the potential for scalability as well as environmentally friendly industrial applications of lichen-dyes. Keywords: Adsorption kinetics; Sustainable dye; Lichen; Molecular docking.