In the present study, Tl4CdI6 nanostructures were synthesized via a facile sonochemical method. The effect of molar ratio of TlI to CdI2, reaction time, power of sonication, and the capping agents was investigated on morphology, size, and purity of the products. The as-prepared nanomaterials were characterized by X-ray diffraction, X-ray energy dispersive spectroscopy, field emission scanning, transmission electron microscopy, and Raman spectroscopy. The optical property of Tl4CdI6 nanoparticles was investigated by ultraviolet-visible spectroscopy (UV-vis), and the band gap was estimated about 2.82 eV. The photocatalytic behaviors of the nanoparticles were investigated by removal and degradation of different organic dyes under the UV irradiation. The results indicated a highest degradation for acid black 1 of 85.7% in 110 min. This sample was selected as an optimum sample for photocatalytic application.