We have demonstrated the crucial role of nitrogen vacancies toward the enhancement of the plasmonic properties of Au/g-C3N4 nanocomposites, which were prepared via the alkali-assisted synthesis and postcalcination pathway, for the effective production of hydrogen through a photocatalytic process under simulated solar light. The resulting material consisted of the nitrogen defective crumpled nanolayers of g-C3N4 with strongly integrated Au plasmonic nanoparticles. It is realized from the studies that the nitrogen vacancies facilitate a stronger interaction with Au NPs and create the coexistence of the states of Au and Au(delta-), which is eventually found to be the origin of the observed enhanced plasmonic properties of the nanocomposite. Such features have not been observed in any other conventional methods for the preparation of Au/g-C3N4, where it significantly improved (i) the light utilization abilities of the materials and (ii) electron-hole generation and separation, which collectively led to the boosting of the photocatalytic performance toward hydrogen production under simulated solar light.