Designing and fabricating hybrid systems with a visible light active semiconductor as one of its components is an important research area for the development of highly efficient photocatalysts. Herein, we report visible-light driven photocatalytic activity of graphene oxide (GO) and controllably reduced GO (rGO) modified Ag₃PO₄ composites fabricated by an in situ method. Concentration of graphene derivatives in GO/rGO–Ag₃PO₄ composites was in the range of 0.13–0.52 wt% which is very minute compared to those reported previously. The optimal concentration of GO in Ag₃PO₄ with a kinetics (k = 1.23 ± 0.04 min⁻¹) for the degradation of rhodamine B is 0.26 wt%. GO–Ag₃PO₄ photocatalysts display an improved catalytic activity compared with pristine and rGOs modified Ag₃PO₄. In line with this, GO/rGO–Ag₃PO₄ composites show improved photocatalytic activity for the degradation of 2-chlorophenol compared with Degussa P-25. Our experiments with GO reduced to different extents show that, rGO with more polar functional groups exhibits a higher photocatalytic efficiency. The photocatalytic activity in the presence of different scavengers reveals that holes and O₂⁻˙ reactive species play major roles in the degradation phenomenon. In view of our experimental results and reported theoretical studies, a change in conduction band energy level and variation in the contribution of different charge orbitals (C 2p and O 2p) to the conduction band in the composite favours electron flow from graphene derivatives to the semiconductor, enhancing its photocatalytic response.