We prepared a new p–n heterojunction photocatalysts p-CuBi2O4/n-NaTaO3 by a simple grinding–annealing method. The photocatalysts showed high photocatalytic activity under visible-light irradiation. Display omitted ► A novel p–n heterojunction photocatalyst p-CuBi2O4/n-NaTaO3 was prepared. ► The photocatalyst was prepared by a simple and safe grinding–annealing method. ► High activity for the photodegradation of MB under visible light irradiation. In this study, a series of p-CuBi2O4/n-NaTaO3 heteronanostructures were synthesized with the grinding–annealing method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalysts exhibit enhanced photocatalytic activity for methyl blue dye degradation under visible-light irradiation. The highest photocatalytic degradation efficiency was observed when the sample calcined at 500°C with 50wt.% CuBi2O4 content. On the basis of the calculated energy band positions, the mechanism of enhanced photocatalytic activity was discussed.