The present work demonstrates preparation of novel ternary ZnO/AgI/Fe3O4 nanocomposites, as magnetically separable visible-light-driven photocatalysts using ultrasonic irradiation method. The XRD, EDX, SEM, TEM, UV-vis DRS, FT-IR, PL, and VSM techniques was applied for characterization of structure, purity, morphology, optical, and magnetic properties of the resultant samples. The superior activity was seen for the nanocomposite with 8 weight ratio of ZnO/AgI to Fe3O4 in degradation of rhodamine B under visible-light irradiation. Photocatalytic activity of this nanocomposite in degradation of rhodamine B, methylene blue, and methyl orange is about 32, 6, and 5-fold higher than that of the ZnO/Fe3O4 nanocomposite. The highly enhanced activity of the ternary magnetic photocatalyst was mainly attributed to more visible-light absorption ability and efficiently separation of the charge carriers. Furthermore, it was revealed that the ultrasonic irradiation time and calcination temperature affect largely on the photocatalytic activity. Finally, the magnetic photocatalyst was successfully separated from the treated solution using external magnetic field. (C) 2015 Elsevier Inc. All rights reserved.