Environmental photocatalysis of wastewater is an important application of TiO₂ nanoparticles (NPs). This paper reports the microwave-assisted green synthesis of TiO₂ NPs using the isolated extract of Permelia perleta lichen. Development of TiO₂ NPs was confirmed using Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, and ultraviolet–visible (UV–Vis) spectroscopy. The acquired TiO₂ NPs were utilized as a nano photocatalyst in the degradation of acridine orange and phenol red dyes as model organic pollutants. The degradation efficiency of the developed TiO₂ NPs was evaluated using a UV–Vis spectrophotometer. We found that the acquired TiO₂ NPs had an average particle size of 30–40 nm, and the nanoparticles were somewhat agglomerated and are nonuniform in shape. The developed nano photocatalyst degraded the selected dyes efficiently, and the degradation efficiency was much better when the test sample was irradiated with UV light with a wavelength of 310 nm.