A promising approach to solving the environmental problems brought on by the burning of fossil fuels and industrial pollution is photocatalysis. Metal chalcogenides and halides have undergone several attempts to increase their photocatalytic activity, including doping them with metals or nonmetals. More particularly, we have covered in-depth synthesis techniques for rare-earth-doped photocatalysts that have been used in recent decades in this chapter. The benefit of doping photocatalytic nanomaterials with rare-earth metals is that the presence of 4f empty orbitals makes them easily mix with functional groups. Due to the doping, a shift in the absorbance is observed toward the near-infrared as well as visible region, making photocatalysis in this area particularly prominent. It has been carefully investigated how doping of rare-earth affects the bandgap and charge carrier recombination rate of several nanomaterials. The future research’s potential has been briefly discussed to improve the photocatalytic performance of various nanocatalysts in the outlook section. The methodology and findings of this work are expected to inspire scientists to investigate an entirely different class of rare-earth-doped nanomaterials for successful photocatalytic applications.