The alarming energy crises has forced the scientific community to work for sustainable energy modules to meet energy requirements. As for this, ZnO/g-C₃N₄ nanocomposites with proper heterojunction were fabricated by coupling a proper amount of ZnO with 2D graphitic carbon nitride (g-C₃N₄) nanosheets and the obtained nanocomposites were applied for photocatalytic hydrogen generation from water under visible light illumination (λ > 420 nm). The morphologies and the hydrogen generation performance of fabricated photocatalysts were characterized in detail. Results showed that the optimized 5ZnO/g-C₃N₄ nanocomposite produced 70 µmol hydrogen gas in 1 h compare to 8 µmol by pure g-C₃N₄ under identical illumination conditions in the presence of methanol without the addition of cocatalyst. The much improved photoactivities of the nanocomposites were attributed to the enhanced charge separation through the heterojunction as confirmed from photoluminescence study, capacity of the fabricated samples for •OH radical generation and steady state surface photovoltage spectroscopic (SS-SPS) measurements. We believe that this work would help to fabricate low cost and effective visible light driven photocatalyst for energy production.