To address the environmental hazard posed by the discharge of textile industry wastewater, we combined n-type (CdSe) and n-type (Ag3PO4) visible-light-responsive semiconductors to produce a photochemically stable n-n type heterostructured nanohybrid comprising metallic Ag (CdSe/Ag/Ag3PO4, CAA) and employed this material as a catalyst for the decomposition of phenol and rhodamine B (RhB). The physicochemical properties of CAA and reference photocatalysts were investigated using instrumental techniques. Compared to individual Ag3PO4 and CdSe, CAA showed an elevated photocatalytic decomposition efficiency for both target pollutants, which was mainly attributed to increased charge separation efficiency and explained by the operation of the Z-scheme reaction mechanism. Moreover, we probed the effects of initial pollutant concentration, AgNO3:NaH2PO4 molar ratio, and the CdSe:Ag3PO4 mass ratio of CAA on catalytic performance. Recycling tests revealed the high photochemical stability of CAA, which was ascribed to the prevention of Ag3PO4 photoreduction by electrons. Finally, a Z-scheme mechanism with vectorial charge transfer suggested for the visible-light-driven decomposition of pollutants over CAA nanohybrids was systematically discussed based on the results of scavenger tests and photoluminescence emission spectra analysis, and an explanation of the role of metallic Ag as a charge mediator was provided.