Novel heterogeneous photocatalyst has been synthesized using g-C3N5, Gd2O3, and MoS2 to examine visible light-driven photocatalytic activity. Each catalyst was made solely. To begin, g-C3N5 was synthesized from amine substituted triazole compound. Green synthesis was adopted to synthesize Gd2O3 with Cocos nucifera coir extract. The hydrothermal process was employed to synthesize MoS2 nanosheets. To synthesize g-C3N5/Gd2O3/MoS2, the synthesised g-C3N5, Gd2O3, and MoS2 nanocomposite were mixed and ultrasonicated. The prepared catalyst was tested in the photocatalytic degradation of methylene blue. Scavenger studies have also been performed for the degradation process. Various spectroscopic studies were used to analyse the synthesized nanomaterials. The morphological studies and heterostructure formation were analysed by FE-SEM with EDS mapping. The surface charge was studied using the Zeta potential. The PL emission and EIS spectra of the g-C3N5/Gd2O3/MoS2 nanocomposite speculated the increase the charge separation, decreased photogenerated electron-hole pair recombination and photo-induced charge transfer. The g-C3N5/Gd2O3/MoS2 nanocomposite has proved to be an excellent photocatalyst for MB degradation.