From the environmental and economic points of view, substitute fuel production has become one of the biggest concerns over the past decades. This work presents two photocatalytic nanocomposites, which can be utilized to generate hydrogen, an alternative fuel source. Fe2O3 and Fe3O4 were supported on carbon nitride nanotubes (C3N4 NTs) via the impregnation method for hydrogen generation under visible-light irradiation. The photocatalytic activity of C3N4 NTs, Fe2O3/C3N4 NTs, and Fe3O4/C3N4 NTs for hydrogen generation was evaluated at various percentages of loaded Fe2O3 and Fe3O4. Fe3O4/C3N4 NTs with 3% mass content of Fe3O4 has been shown to yield the highest photocatalytic performance, 1.9-fold that of the bare C3N4 NTs, and also showed exceptional stability with almost no change after three runs. The improved activity of Fe3O4/C3N4 NTs compared to that of Fe2O3/C3N4 NTs could be credited to the higher usage of visible-light radiation and efficient electron–hole pair separation, which is supported by comprehensive characterization results, leading to a lower recombination rate. The possible mechanism of the composite was also elucidated.