The photo-degradation of methylene blue (MB) dye solution is studied under UV light irradiation using a TiO₂-Mica composite calcined at 450 °C (TiO₂-M 450). X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FTIR), and UV spectroscopy are used to study the photocatalyst after it is made. XRD shows TiO₂ nanoparticles (NPs) are in the anatase and rutile phases. MB degradation is evaluated by different parameters, including the concentration of MB dye, pH, the amount of photocatalyst used, and the effect of the oxidant (hydrogen peroxide, H₂O₂). Under moderate exposure to UV light, the TiO₂-M 450 composite can remove approximately 99.2% of MB dye (1.0 × 10⁻⁴ M) for 80 min. The optimal amount of TiO₂-M 450 composite is 5.0 g L⁻¹, corresponding to 2.0 g L⁻¹ of TiO₂ NPs. MB dyes can be treated with a simple, successful, and effective process. The nanocomposite is thought to be a good candidate for a photocatalyst that could be used to clean up the environment.