A carbon quantum dot (CQDs)/AgPO/BiPO heterostructure photocatalyst was constructed by a simple hydrothermal synthesis method. The as-prepared CQDs/AgPO/BiPO photocatalyst has been characterized in detail by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and photoelectrochemical measurements. It is demonstrated that the CQDs/AgPO/BiPO composite is constructed by assembling AgPO fine particles and CQDs on the surface of rice-like BiPO granules. The CQDs/AgPO/BiPO heterostructure photocatalyst exhibits a higher photocatalytic activity for the degradation of the rhodamine B dye than that of AgPO, BiPO, and AgPO/BiPO. The synergistic effects of light absorption capacity, band edge position, separation, and utilization efficiency of photogenerated carriers play the key role for the enhanced photodegradation of the rhodamine B dye.