Graphene-analogues BN modified Ag₃PO₄ photocatalysts were successfully prepared. The composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (DRS), Fourier transformed infrared (FT-IR) spectroscopy and photoelectrochemical experiments. The results showed that after adding a small amount of graphene-analogue BN, the composite photocatalysts exhibited significantly enhanced photocatalytic activity and good stability for the photocatalytic degradation of RhB. The 0.5 wt% BN content sample showed the best photocatalytic activity. The increasing photocatalytic efficiency of the graphene-analogue BN/Ag₃PO₄ photocatalyst could be attributed to the synergetic role between graphene-analogue BN and Ag₃PO₄, which suppressed the recombination of photogenerated electron–hole pairs. It was found that the photocatalytic degradation of RhB by the photocatalyst followed pseudo-first-order kinetics. The photocatalytic mechanism of the graphene-analogue BN/Ag₃PO₄ composite was also investigated.