The Fenton process is one of the most prominent advanced oxidation techniques for the treatment of wastewater in industrial effluents. Also, the traditional homogeneous Fenton process possesses a few limitations, such as sludge formation, and addition of catalyst for every batch of treatment. To address these heterogeneous recyclable Fenton processes, Fe3O4/g-C3N4 nanocomposites have been developed. The Fe3O4 nanoparticles here have been prepared by a simple sol-gel technique with a single ion precursor. The nanoparticles formed were polycrystalline and determined the particles to be nearly 30 nm in size. The purity and crystalline nature of the samples was examined, which was confirmed by XRD, FTIR, and EDAX analysis. The composites were prepared using melamine-derived g-C3N4 using a simple ultrasonication technique. 3, 5, 10, and 30 wt% Fe3O4 nanoparticles were incorporated in the g-C3N4 matrix, and their Fenton, photo, and photo-Fenton processes were studied using rhodamine dye. The 5 wt% composite showed superior performance with 98% degradation efficiency within 30 minutes. It also showed a 1.24 and 2.15-fold increase in the rate constant when compared to pure Fe2O3 and g-C3N4 samples, respectively. Their super-paramagnetic properties help in the easy separation of the catalyst after the reaction. The catalyst also has at least five times the re-usability in the photoFenton process. These results may help us understand and develop iron-based heterogeneous systems for advanced oxidation processes.