Introduction: Designing an effective photocatalyst for hydrogen (H2) performance under visible irradiation with a decrease the bandgap energy of semiconductor has been considered as an essential aspect in boosting the performance of photocatalytic reactions for hydrogen performance from the water-splitting process. Herein, we focus on evaluating the role of doping with Ir into SrTiO3 structure fabricated by the hydrothermal method for H2 generation. Methods: The crystalline characteristics of the Ir-SrTiO3 photocatalyst were carried out via X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The chemical composition and the optical properties of the Ir-SrTiO3 were classified by energy-dispersive X-ray spectroscopy (EDX) and UV-Vis spectra, respectively. Results: The results showcased that the dramatically improved absorbing performances of Ir/SrTiO3 specimen were observed. This could be governed by the presence of Ir impurity states in the forbidden energy gap, causing a decrease in the energy gap of SrTiO3. This work also revealed that Ir doped into SrTiO3 nanocube structure exhibited excellent photocatalytic H2 evolution compared with pristine SrTiO3 (~454 and ~325 mmol.h−1 .g−1 H2 production under UV and visible light irradiation, respectively). A rational photocatalytic mechanism is projected to be able to provide significant awareness for further research. Conclusion: The results are believed to be the role of Ir states and nanocube structures of SrTiO3 as a new approach in renewable energy resources.