Ag/AgBr photocatalysts are prepared by a ionic‐liquid‐assisted hydrothermal method. The as‐prepared photocatalysts are characterized by scanning electron microscopy, X‐ray powder diffraction, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller measurement, and diffuse reflectance spectroscopy. Ag/AgBr exhibits significant photocatalytic activity toward degradation of imidacloprid under visible light. After 9 h, the conversion percentage of imidacloprid reaches 90%. Besides, the cycle performances suggest a good stability of the catalyst. The photocatalytic kinetics indicate that the degradation processes follow pseudo‐first‐order kinetics. According to the fact that electron holes •OH and •O2− greatly promote the photodegradation process, the degradation mechanism is proposed.