A novel 3D p–n heteroarchitecture Ag₃PO₄/Ta₃N₅ composite photocatalyst with double visible-light-response characteristics has been prepared using an in situ template-free precipitation method. It is found that the fascinating Ag₃PO₄/Ta₃N₅ exhibited high superior photoactivity and photostability compared to bare Ag₃PO₄ and Ta₃N₅ for the degradation of RhB under visible light irradiation. The improved performance of the composite is primarily attributable to sufficient visible-light harvesting, efficient charge separation and transfer of photogenerated electrons and holes resulting from matched energy bandgaps and sufficient p–n hetero-interfaces between Ag₃PO₄ and Ta₃N₅. The quenching effects of different scavengers demonstrate that the reactive h⁺ and O₂⁻˙ species played a major role in the photodegradation process. It is expected that the 3D p–n heterostructure composite fabricated via a facile precipitation method, may be a promising candidate for organic pollutant degradation.