A novel visible-light-sensitive BiOI/BiVO₄ photocatalyst with a p–n heterojunction structure was synthesized through a facile coprecipitation method. The physical and chemical properties of as-synthesized BiOI/BiVO₄ composites were characterized by XRD, XPS, BET, SEM, EDS, HRTEM, photoluminescence spectrum and UV–DRS respectively. The photocatalytic activity of the prepared photocatalysts was evaluated by photodegrading methylene blue and killing of Pseudomonas aeruginosa (P. aeruginosa) under visible light irradiation. The results showed that the 30%BiOI/BiVO₄ (molar ratio of I:V = 3:7) exhibits the higher photocatalytic activity than the pristine BiOI and BiVO₄. Moreover, the sterilization mechanism involved in the photocatalytic disinfection process was studied by captive species trapping experiments. The result revealed that hydroxyl radical (OH) and holes (h⁺) are the main reactive species for killing of P. aeruginosa under visible light irradiation. In addition, after five recycles for killing of P. aeruginosa under visible light irradiation, 30%BiOI/BiVO₄ does not exhibit significant loss of photocatalytic activity. The results confirm that the synthesized 30%BiOI/BiVO₄ photocatalyst has long-time reusability and good photocatalytic stability. The photocatalyst shows potential application in marine antifouling.