Population growth, climate change, and global warming have led researchers to be interested in utilizing eco-friendly methods for the nitrogen reduction process. It has found that nitrogen molecule can be converted into ammonia in ambient conditions using photocatalysts under visible light. In the present work, a novel visible-light active nanocomposite was fabricated, in which different percentages of Ni3V2O8 nanoparticles (10, 15, 20, and 30%) were decorated on graphitic carbon nitride nanosheets (abbreviated as NGCN/NiVO). Then, morphology, textural, optical properties, and crystal structure of the photocatalysts were studied in detail. The results displayed that the NGCN/NiVO (20%) photocatalyst has significant catalytic performance in the ammonia generation process in comparison with the NGCN and GCN, which is 2.3 and 8 times higher, respectively. The stability of NGCN/NiVO (20%) nanocomposite, as a vital parameter, was evaluated for five runs. Also, the impact of electron scavengers, solvent, and pH of media was examined. Finally, a possible mechanism for the considerable enhancement of nitrogen photofixation efficiency was suggested.