Decorated ternary Pd@CdS@Fe₃O₄ nanoarchitectures are synthesized by judicious loading of CdS nanoparticles without functionalizing the surface of the base materials, i.e., Fe₃O₄ and CdS. Here we have adopted a unique method to prepare Fe₃O₄ nanoparticles. In this ternary composite ferromagnetic Fe₃O₄ behaves as the catalyst carrier, CdS is used as semiconductor, and loaded Pd due to its high electron affinity behaves as a electron scavenger. CdS inherits visible light absorbing capability. Here Pd²⁺ is reduced to Pd upon deposition onto the CdS nanoparticles by the anionic S²⁻. Then the ternary composite exhibits pronounced photocatalytic activity toward Rhodamine B oxidation under visible light irradiation in the yellow region. This composite happens to be much more efficient than that of pure CdS and CdS@Fe₃O₄ composite. Metallic Pd, due to its high electron withdrawing property, uptakes the electrons from the conduction band of CdS and increases the oxidative power of CdS. Because of the presence of Fe₃O₄ in the composite, the catalyst shows ferromagnetism, and thus after the photocatalytic experiments the catalyst is easily isolated from the reaction mixture. The efficiency of the photocatalyst decreases after five cycles because of the disintegration of the particle. The ternary composite serves as a convenient and efficient photocatalyst for degradation of dye molecules leading to the purification of water.