The overuse and dissemination of antibiotics caused serious threats to the environment and public health. In this work, a molybdenum disulfide-magnetic spinel ferrite composite (MoS2/CdFe2O4) with a low bandgap was designed and prepared by a two-step hydrothermal method. Compared with MoS2, CdFe2O4 and other MoS2/CdFe2O4 composites, the 60% MoS2/CdFe2O4 composite showed best visible light induced photocatalytic activity towards tetracycline (TC) degradation reaction. More than 87% of TC (25 ppm) can be degraded under visible light till 120 min. The degradation of TC over the MoS2/CdFe2O4 composites followed the pseudo-first-order kinetics. The 60% MoS2/CdFe2O4 composite had largest apparent reaction rate constant of 11.36 × 10−3 min−1. Due to its magnetic property, the MoS2/CdFe2O4 composite with saturation magnetization value of 7.0 emu g−1 can be separated easily from water and reused. Based on the band structure and active species analysis, a Z-scheme structure was formed in the MoS2/CdFe2O4 composite, which accelerated photocatalytic oxidation. The hydroxyl radicals (˙OH) were detected under visible light irradiation and provided strong photocatalytic oxidation performance. This work may provide new ideas for designing visible light responsive and magnetic CdFe2O4 photocatalysts.