Vertically aligned Bi2S3 platelets have been synthesized on FTO substrate via a simple hydrothermal process. X-ray diffraction analysis confirms the orthorhombic structure of the platelets. The results of scanning electron microscopy show that the Bi2S3 platelets interconnect with each other. The length of platelets is about 5 μm and the thickness ranges from 50 to 150 nm. The photocatalytic activity studies reveal that the synthesized Bi2S3 platelets exhibit excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under UV irradiation. A degradation ratio of 56% was obtained for the Bi2S3 platelets at 120 min and about 99% at 240 min. These results suggest that Bi2S3 platelets will be an interesting candidate for photocatalytic detoxification under UV light.