In the present work, metal (Pt and Au) and alloy (PtAu) NPs-integrated g-C3N4 hybrids were synthesized via a solvothermal method. By varying the initial Pt and Au precursor concentrations, the content of Pt and Au was varied in the bimetallic alloys to find an optimum content for the highest photoactivity toward H2 generation through water splitting. The optimized PtAu alloy NPs-integrated g-C3N4 exhibits 10 times higher photocatalytic H2 evolution as compared to the pristine g-C3N4. This was due to higher light absorption ability, leading to formation of a greater number of charge carriers and superior charge transport properties as confirmed from the PL and EIS measurements. This study can be used as a step to understand the improved photocatalytic activity upon integrating metal and metal alloy NPs to g-C3N4 sheets which can be further useful for the development of catalysts.